Vulnerabilities > CVE-2020-8492 - Resource Exhaustion vulnerability in multiple products
Attack vector
NETWORK Attack complexity
LOW Privileges required
NONE Confidentiality impact
NONE Integrity impact
NONE Availability impact
HIGH Summary
Python 2.7 through 2.7.17, 3.5 through 3.5.9, 3.6 through 3.6.10, 3.7 through 3.7.6, and 3.8 through 3.8.1 allows an HTTP server to conduct Regular Expression Denial of Service (ReDoS) attacks against a client because of urllib.request.AbstractBasicAuthHandler catastrophic backtracking.
Vulnerable Configurations
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- XML Ping of the Death An attacker initiates a resource depletion attack where a large number of small XML messages are delivered at a sufficiently rapid rate to cause a denial of service or crash of the target. Transactions such as repetitive SOAP transactions can deplete resources faster than a simple flooding attack because of the additional resources used by the SOAP protocol and the resources necessary to process SOAP messages. The transactions used are immaterial as long as they cause resource utilization on the target. In other words, this is a normal flooding attack augmented by using messages that will require extra processing on the target.
- XML Entity Expansion An attacker submits an XML document to a target application where the XML document uses nested entity expansion to produce an excessively large output XML. XML allows the definition of macro-like structures that can be used to simplify the creation of complex structures. However, this capability can be abused to create excessive demands on a processor's CPU and memory. A small number of nested expansions can result in an exponential growth in demands on memory.
- Inducing Account Lockout An attacker leverages the security functionality of the system aimed at thwarting potential attacks to launch a denial of service attack against a legitimate system user. Many systems, for instance, implement a password throttling mechanism that locks an account after a certain number of incorrect log in attempts. An attacker can leverage this throttling mechanism to lock a legitimate user out of their own account. The weakness that is being leveraged by an attacker is the very security feature that has been put in place to counteract attacks.
- Violating Implicit Assumptions Regarding XML Content (aka XML Denial of Service (XDoS)) XML Denial of Service (XDoS) can be applied to any technology that utilizes XML data. This is, of course, most distributed systems technology including Java, .Net, databases, and so on. XDoS is most closely associated with web services, SOAP, and Rest, because remote service requesters can post malicious XML payloads to the service provider designed to exhaust the service provider's memory, CPU, and/or disk space. The main weakness in XDoS is that the service provider generally must inspect, parse, and validate the XML messages to determine routing, workflow, security considerations, and so on. It is exactly these inspection, parsing, and validation routines that XDoS targets. There are three primary attack vectors that XDoS can navigate Target CPU through recursion: attacker creates a recursive payload and sends to service provider Target memory through jumbo payloads: service provider uses DOM to parse XML. DOM creates in memory representation of XML document, but when document is very large (for example, north of 1 Gb) service provider host may exhaust memory trying to build memory objects. XML Ping of death: attack service provider with numerous small files that clog the system. All of the above attacks exploit the loosely coupled nature of web services, where the service provider has little to no control over the service requester and any messages the service requester sends.
Nessus
NASL family Huawei Local Security Checks NASL id EULEROS_SA-2020-1346.NASL description According to the versions of the python3 packages installed, the EulerOS Virtualization for ARM 64 installation on the remote host is affected by the following vulnerabilities : - In Python (CPython) 3.6 through 3.6.10, 3.7 through 3.7.6, and 3.8 through 3.8.1, an insecure dependency load upon launch on Windows 7 may result in an attacker last seen 2020-04-07 modified 2020-04-02 plugin id 135133 published 2020-04-02 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/135133 title EulerOS Virtualization for ARM 64 3.0.6.0 : python3 (EulerOS-SA-2020-1346) NASL family Amazon Linux Local Security Checks NASL id AL2_ALAS-2020-1432.NASL description http.cookiejar.DefaultPolicy.domain_return_ok in Lib/http/cookiejar.py in Python before 3.7.3 does not correctly validate the domain: it can be tricked into sending existing cookies to the wrong server. An attacker may abuse this flaw by using a server with a hostname that has another valid hostname as a suffix (e.g., pythonicexample.com to steal cookies for example.com). When a program uses http.cookiejar.DefaultPolicy and tries to do an HTTP connection to an attacker-controlled server, existing cookies can be leaked to the attacker. This affects 2.x through 2.7.16, 3.x before 3.4.10, 3.5.x before 3.5.7, 3.6.x before 3.6.9, and 3.7.x before 3.7.3.(CVE-2018-20852) Python 2.7 through 2.7.17, 3.5 through 3.5.9, 3.6 through 3.6.10, 3.7 through 3.7.6, and 3.8 through 3.8.1 allows an HTTP server to conduct Regular Expression Denial of Service (ReDoS) attacks against a client because of urllib.request.AbstractBasicAuthHandler catastrophic backtracking.(CVE-2020-8492) last seen 2020-06-10 modified 2020-06-04 plugin id 137089 published 2020-06-04 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/137089 title Amazon Linux 2 : python (ALAS-2020-1432) NASL family SuSE Local Security Checks NASL id SUSE_SU-2020-0854-1.NASL description This update for python3 fixes the following issue : CVE-2019-18348: Fixed a CRLF injection via the host part of the url passed to urlopen(). Now an InvalidURL exception is raised (bsc#1155094). CVE-2019-9674: Improved the documentation to reflect the dangers of zip-bombs (bsc#1162825). CVE-2020-8492: Fixed a regular expression in urllib that was prone to denial of service via HTTP (bsc#1162367). Fixed an issue with version missmatch (bsc#1162224). Rename idle icons to idle3 in order to not conflict with python2 variant of the package. (bsc#1165894) Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues. last seen 2020-04-10 modified 2020-04-03 plugin id 135197 published 2020-04-03 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/135197 title SUSE SLES12 Security Update : python3 (SUSE-SU-2020:0854-1) NASL family Fedora Local Security Checks NASL id FEDORA_2020-6A88DAD4A0.NASL description ## Python 3.8.3 This is the third maintenance release of Python 3.8. See [the changelog](https://docs.python.org/release/3.8.3/whatsnew/changelog.ht ml#changelog) for details. Contains the security fix for CVE-2020-8492. Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues. last seen 2020-06-06 modified 2020-05-29 plugin id 136954 published 2020-05-29 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/136954 title Fedora 31 : python38 (2020-6a88dad4a0) NASL family PhotonOS Local Security Checks NASL id PHOTONOS_PHSA-2020-1_0-0288_PYTHON2.NASL description An update of the python2 package has been released. last seen 2020-04-22 modified 2020-04-15 plugin id 135492 published 2020-04-15 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/135492 title Photon OS 1.0: Python2 PHSA-2020-1.0-0288 NASL family Fedora Local Security Checks NASL id FEDORA_2020-98E0F0F11B.NASL description ## Python 3.8.3 This is the third maintenance release of Python 3.8. See [the changelog](https://docs.python.org/release/3.8.3/whatsnew/changelog.ht ml#changelog) for details. Contains the security fix for CVE-2020-8492. Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues. last seen 2020-06-10 modified 2020-06-04 plugin id 137118 published 2020-06-04 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/137118 title Fedora 32 : python3 (2020-98e0f0f11b) NASL family SuSE Local Security Checks NASL id OPENSUSE-2020-274.NASL description This update for python3 fixes the following issues : Security issues fixed : - CVE-2019-9674: Improved the documentation to reflect the dangers of zip-bombs (bsc#1162825). - CVE-2020-8492: Fixed a regular expression in urrlib that was prone to denial of service via HTTP (bsc#1162367). Non-security issue fixed : - If the locale is last seen 2020-03-18 modified 2020-03-02 plugin id 134197 published 2020-03-02 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/134197 title openSUSE Security Update : python3 (openSUSE-2020-274) NASL family FreeBSD Local Security Checks NASL id FREEBSD_PKG_A27B0BB684FC11EAB5B4641C67A117D8.NASL description Ben Caller and Matt Schwager reports : Python 2.7 through 2.7.17, 3.5 through 3.5.9, 3.6 through 3.6.10, 3.7 through 3.7.6, and 3.8 through 3.8.1 allows an HTTP server to conduct Regular Expression Denial of Service (ReDoS) attacks against a client because of urllib.request.AbstractBasicAuthHandler catastrophic backtracking. last seen 2020-06-10 modified 2020-04-24 plugin id 135944 published 2020-04-24 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/135944 title FreeBSD : Python -- Regular Expression DoS attack against client (a27b0bb6-84fc-11ea-b5b4-641c67a117d8) NASL family Ubuntu Local Security Checks NASL id UBUNTU_USN-4333-2.NASL description USN-4333-1 fixed vulnerabilities in Python. This update provides the corresponding update for Ubuntu 20.04 LTS. Original advisory details : It was discovered that Python incorrectly stripped certain characters from requests. A remote attacker could use this issue to perform CRLF injection. (CVE-2019-18348) It was discovered that Python incorrectly handled certain HTTP requests. An attacker could possibly use this issue to cause a denial of service. (CVE-2020-8492). Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues. last seen 2020-05-08 modified 2020-05-01 plugin id 136281 published 2020-05-01 reporter Ubuntu Security Notice (C) 2020 Canonical, Inc. / NASL script (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/136281 title Ubuntu 20.04 : python3.8 vulnerabilities (USN-4333-2) NASL family PhotonOS Local Security Checks NASL id PHOTONOS_PHSA-2020-3_0-0078_PYTHON2.NASL description An update of the python2 package has been released. last seen 2020-04-30 modified 2020-04-21 plugin id 135784 published 2020-04-21 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/135784 title Photon OS 3.0: Python2 PHSA-2020-3.0-0078 NASL family PhotonOS Local Security Checks NASL id PHOTONOS_PHSA-2020-2_0-0226_PYTHON3.NASL description An update of the python3 package has been released. last seen 2020-04-14 modified 2020-04-10 plugin id 135299 published 2020-04-10 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/135299 title Photon OS 2.0: Python3 PHSA-2020-2.0-0226 NASL family Gentoo Local Security Checks NASL id GENTOO_GLSA-202005-09.NASL description The remote host is affected by the vulnerability described in GLSA-202005-09 (Python: Denial of Service) An issue was discovered in urllib.request.AbstractBasicAuthHandler which allowed a remote attacker to send malicious data causing extensive regular expression backtracking. Impact : An attacker could cause a possible Denial of Service condition. Workaround : There is no known workaround at this time. last seen 2020-05-21 modified 2020-05-15 plugin id 136639 published 2020-05-15 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/136639 title GLSA-202005-09 : Python: Denial of Service NASL family Huawei Local Security Checks NASL id EULEROS_SA-2020-1427.NASL description According to the versions of the python packages installed, the EulerOS installation on the remote host is affected by the following vulnerabilities : - The Wave_read._read_fmt_chunk function in Lib/wave.py in Python through 3.6.4 does not ensure a nonzero channel value, which allows attackers to cause a denial of service (divide-by-zero and exception) via a crafted wav format audio file. NOTE: the vendor disputes this issue because Python applications last seen 2020-05-06 modified 2020-04-15 plugin id 135556 published 2020-04-15 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/135556 title EulerOS 2.0 SP3 : python (EulerOS-SA-2020-1427) NASL family Huawei Local Security Checks NASL id EULEROS_SA-2020-1321.NASL description According to the version of the python packages installed, the EulerOS installation on the remote host is affected by the following vulnerability : - Python 2.7 through 2.7.17, 3.5 through 3.5.9, 3.6 through 3.6.10, 3.7 through 3.7.6, and 3.8 through 3.8.1 allows an HTTP server to conduct Regular Expression Denial of Service (ReDoS) attacks against a client because of urllib.request.AbstractBasicAuthHandler catastrophic backtracking.(CVE-2020-8492) Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues. last seen 2020-05-06 modified 2020-03-23 plugin id 134812 published 2020-03-23 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/134812 title EulerOS 2.0 SP5 : python (EulerOS-SA-2020-1321) NASL family SuSE Local Security Checks NASL id SUSE_SU-2020-0510-1.NASL description This update for python fixes the following issues : Security issues fixed : CVE-2019-9674: Improved the documentation, warning about dangers of zip-bombs (bsc#1162825). CVE-2020-8492: Fixed a regular expression in urrlib that was prone to denial of service via HTTP (bsc#1162367). Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues. last seen 2020-03-18 modified 2020-02-28 plugin id 134159 published 2020-02-28 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/134159 title SUSE SLED15 / SLES15 Security Update : python (SUSE-SU-2020:0510-1) NASL family PhotonOS Local Security Checks NASL id PHOTONOS_PHSA-2020-3_0-0078_PYTHON3.NASL description An update of the python3 package has been released. last seen 2020-04-30 modified 2020-04-21 plugin id 135785 published 2020-04-21 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/135785 title Photon OS 3.0: Python3 PHSA-2020-3.0-0078 NASL family SuSE Local Security Checks NASL id SUSE_SU-2020-0557-1.NASL description This update for python36 fixes the following issues : Security issues fixed : CVE-2019-9674: Improved the documentation to reflect the dangers of zip-bombs (bsc#1162825). CVE-2020-8492: Fixed a regular expression in urrlib that was prone to denial of service via HTTP (bsc#1162367). Non-security issue fixed: If the locale is last seen 2020-03-18 modified 2020-03-06 plugin id 134286 published 2020-03-06 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/134286 title SUSE SLES12 Security Update : python36 (SUSE-SU-2020:0557-1) NASL family Huawei Local Security Checks NASL id EULEROS_SA-2020-1516.NASL description According to the versions of the python packages installed, the EulerOS Virtualization for ARM 64 installation on the remote host is affected by the following vulnerabilities : - Python Software Foundation Python (CPython) version 2.7 contains a CWE-77: Improper Neutralization of Special Elements used in a Command ( last seen 2020-05-08 modified 2020-05-01 plugin id 136219 published 2020-05-01 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/136219 title EulerOS Virtualization for ARM 64 3.0.2.0 : python (EulerOS-SA-2020-1516) NASL family Huawei Local Security Checks NASL id EULEROS_SA-2020-1472.NASL description According to the versions of the python packages installed, the EulerOS Virtualization installation on the remote host is affected by the following vulnerabilities : - Python Software Foundation Python (CPython) version 2.7 contains a CWE-77: Improper Neutralization of Special Elements used in a Command ( last seen 2020-04-30 modified 2020-04-16 plugin id 135634 published 2020-04-16 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/135634 title EulerOS Virtualization 3.0.2.2 : python (EulerOS-SA-2020-1472) NASL family Huawei Local Security Checks NASL id EULEROS_SA-2020-1295.NASL description According to the versions of the python2 packages installed, the EulerOS installation on the remote host is affected by the following vulnerabilities : - ** DISPUTED ** The Wave_read._read_fmt_chunk function in Lib/wave.py in Python through 3.6.4 does not ensure a nonzero channel value, which allows attackers to cause a denial of service (divide-by-zero and exception) via a crafted wav format audio file. NOTE: the vendor disputes this issue because Python applications last seen 2020-05-03 modified 2020-03-23 plugin id 134787 published 2020-03-23 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/134787 title EulerOS 2.0 SP8 : python2 (EulerOS-SA-2020-1295) NASL family Huawei Local Security Checks NASL id EULEROS_SA-2020-1296.NASL description According to the version of the python3 packages installed, the EulerOS installation on the remote host is affected by the following vulnerability : - Python 2.7 through 2.7.17, 3.5 through 3.5.9, 3.6 through 3.6.10, 3.7 through 3.7.6, and 3.8 through 3.8.1 allows an HTTP server to conduct Regular Expression Denial of Service (ReDoS) attacks against a client because of urllib.request.AbstractBasicAuthHandler catastrophic backtracking.(CVE-2020-8492) Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues. last seen 2020-05-03 modified 2020-03-23 plugin id 134788 published 2020-03-23 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/134788 title EulerOS 2.0 SP8 : python3 (EulerOS-SA-2020-1296) NASL family Huawei Local Security Checks NASL id EULEROS_SA-2020-1344.NASL description According to the versions of the python2 packages installed, the EulerOS Virtualization for ARM 64 installation on the remote host is affected by the following vulnerabilities : - A ZIP bomb attack was found in the Python zipfile module. A remote attacker could abuse this flaw by providing a specially crafted ZIP file that, when decompressed by zipfile, would exhaust system resources resulting in a denial of service.(CVE-2019-9674) - The Wave_read._read_fmt_chunk function in Lib/wave.py in Python through 3.6.4 does not ensure a nonzero channel value, which allows attackers to cause a denial of service (divide-by-zero and exception) via a crafted wav format audio file. NOTE: the vendor disputes this issue because Python applications last seen 2020-04-07 modified 2020-04-02 plugin id 135131 published 2020-04-02 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/135131 title EulerOS Virtualization for ARM 64 3.0.6.0 : python2 (EulerOS-SA-2020-1344) NASL family Ubuntu Local Security Checks NASL id UBUNTU_USN-4333-1.NASL description It was discovered that Python incorrectly stripped certain characters from requests. A remote attacker could use this issue to perform CRLF injection. (CVE-2019-18348) It was discovered that Python incorrectly handled certain HTTP requests. An attacker could possibly use this issue to cause a denial of service. (CVE-2020-8492). Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues. last seen 2020-04-30 modified 2020-04-22 plugin id 135894 published 2020-04-22 reporter Ubuntu Security Notice (C) 2020 Canonical, Inc. / NASL script (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/135894 title Ubuntu 16.04 LTS / 18.04 LTS / 19.10 : python2.7, python3.4, python3.5, python3.6, python3.7 vulnerabilities (USN-4333-1) NASL family SuSE Local Security Checks NASL id SUSE_SU-2020-0467-1.NASL description This update for python3 fixes the following issues : Security issues fixed : CVE-2019-9674: Improved the documentation to reflect the dangers of zip-bombs (bsc#1162825). CVE-2020-8492: Fixed a regular expression in urrlib that was prone to denial of service via HTTP (bsc#1162367). Non-security issue fixed: If the locale is last seen 2020-03-18 modified 2020-02-26 plugin id 134081 published 2020-02-26 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/134081 title SUSE SLED15 / SLES15 Security Update : python3 (SUSE-SU-2020:0467-1)
References
- https://github.com/python/cpython/pull/18284
- https://python-security.readthedocs.io/vuln/urllib-basic-auth-regex.html
- https://bugs.python.org/issue39503
- https://security.netapp.com/advisory/ntap-20200221-0001/
- http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00003.html
- https://usn.ubuntu.com/4333-1/
- https://usn.ubuntu.com/4333-2/
- https://security.gentoo.org/glsa/202005-09
- https://lists.debian.org/debian-lts-announce/2020/07/msg00011.html
- https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/APGWEMYZIY5VHLCSZ3HD67PA5Z2UQFGH/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7WOKDEXLYW5UQ4S7PA7E37IITOC7C56J/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UESGYI5XDAHJBATEZN3MHNDUBDH47AS6/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/A5NSAX4SC3V64PGZUPH7PRDLSON34Q5A/
- https://lists.apache.org/thread.html/rdb31a608dd6758c6093fd645aea3fbf022dd25b37109b6aaea5bc0b5%40%3Ccommits.cassandra.apache.org%3E
- https://lists.apache.org/thread.html/rfec113c733162b39633fd86a2d0f34bf42ac35f711b3ec1835c774da%40%3Ccommits.cassandra.apache.org%3E