Vulnerabilities > CVE-2018-12893

CVSS 6.5 - MEDIUM

Attack vector

LOCAL

Attack complexity

LOW

Privileges required

LOW

Confidentiality impact

NONE

Integrity impact

NONE

Availability impact

HIGH

local

low complexity

xen

debian

nessus

NVD

Published: 2018-07-02

Updated: 2019-10-03

Summary

An issue was discovered in Xen through 4.10.x. One of the fixes in XSA-260 added some safety checks to help prevent Xen livelocking with debug exceptions. Unfortunately, due to an oversight, at least one of these safety checks can be triggered by a guest. A malicious PV guest can crash Xen, leading to a Denial of Service. All Xen systems which have applied the XSA-260 fix are vulnerable. Only x86 systems are vulnerable. ARM systems are not vulnerable. Only x86 PV guests can exploit the vulnerability. x86 HVM and PVH guests cannot exploit the vulnerability. An attacker needs to be able to control hardware debugging facilities to exploit the vulnerability, but such permissions are typically available to unprivileged users.

Vulnerable Configurations

Part	Description	Count
OS	Xen XEN XEN *	1
OS	Debian Debian Debian Linux 9.0	1

Nessus

NASL family	SuSE Local Security Checks
NASL id	OPENSUSE-2018-803.NASL
description	This update for xen fixes the following issues : Security issues fixed : - CVE-2018-3665: Fix Lazy FP Save/Restore issue (XSA-267) (bsc#1095242). - CVE-2018-12891: Fix possible Denial of Service (DoS) via certain PV MMU operations that affect the entire host (XSA-264) (bsc#1097521). - CVE-2018-12892: Fix libxl to honour the readonly flag on HVM emulated SCSI disks (XSA-266) (bsc#1097523). - CVE-2018-12893: Fix crash/Denial of Service (DoS) via safety check (XSA-265) (bsc#1097522). - CVE-2018-11806: Fix heap buffer overflow while reassembling fragmented datagrams (bsc#1096224). Bug fixes : - bsc#1027519: Add upstream patches from January. - bsc#1087289: Fix xen scheduler crash. This update was imported from the SUSE:SLE-12-SP3:Update update project.
last seen	2020-06-05
modified	2018-08-07
plugin id	111565
published	2018-08-07
reporter	This script is Copyright (C) 2018-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/111565
title	openSUSE Security Update : xen (openSUSE-2018-803)

NASL family	SuSE Local Security Checks
NASL id	SUSE_SU-2018-2059-1.NASL
description	This update for xen fixes the following issues: Security issues fixed : - CVE-2018-3665: Fix Lazy FP Save/Restore issue (XSA-267) (bsc#1095242). - CVE-2018-12891: Fix possible Denial of Service (DoS) via certain PV MMU operations that affect the entire host (XSA-264) (bsc#1097521). - CVE-2018-12892: Fix libxl to honour the readonly flag on HVM emulated SCSI disks (XSA-266) (bsc#1097523). - CVE-2018-12893: Fix crash/Denial of Service (DoS) via safety check (XSA-265) (bsc#1097522). - CVE-2018-11806: Fix heap buffer overflow while reassembling fragmented datagrams (bsc#1096224). Bug fixes : - bsc#1027519: Add upstream patches from January. - bsc#1087289: Fix xen scheduler crash. 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	2020-06-01
modified	2020-06-02
plugin id	111348
published	2018-07-26
reporter	This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/111348
title	SUSE SLED12 / SLES12 Security Update : xen (SUSE-SU-2018:2059-1)

NASL family	Fedora Local Security Checks
NASL id	FEDORA_2018-1A467757CE.NASL
description	preemption checks bypassed in x86 PV MM handling [XSA-264, CVE-2018-12891] x86: #DB exception safety check can be triggered by a guest [XSA-265, CVE-2018-12893] libxl fails to honour readonly flag on HVM emulated SCSI disks [XSA-266, CVE-2018-12892] ---- Speculative register leakage from lazy FPU context switching [XSA-267, CVE-2018-3665] fix for change in iasl output 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	2020-06-05
modified	2018-07-24
plugin id	111236
published	2018-07-24
reporter	This script is Copyright (C) 2018-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/111236
title	Fedora 27 : xen (2018-1a467757ce)

NASL family	SuSE Local Security Checks
NASL id	SUSE_SU-2018-2081-1.NASL
description	This update for xen fixes the following issues: Security issues fixed : - CVE-2018-12891: Fix preemption checks bypass in x86 PV MM handling (XSA-264) (bsc#1097521). - CVE-2018-12892: Fix libxl failure to honour readonly flag on HVM emulated SCSI disks (XSA-266) (bsc#1097523). - CVE-2018-12893: Fix #DB exception safety check that could be triggered by a guest (XSA-265) (bsc#1097522). - CVE-2018-11806: Fix heap buffer overflow while reassembling fragmented datagrams (bsc#1096224). - CVE-2018-3665: Fix lazy FP Save/Restore (XSA-267) (bsc#1095242). Bug fixes : - bsc#1027519: Update to Xen 4.7.6 bug fix only release. - bsc#1087289: Xen BUG at sched_credit.c:1663. - bsc#1094725: `virsh blockresize` does not work with Xen qdisks. 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	2020-06-01
modified	2020-06-02
plugin id	111433
published	2018-07-30
reporter	This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/111433
title	SUSE SLES12 Security Update : xen (SUSE-SU-2018:2081-1)

NASL family	SuSE Local Security Checks
NASL id	SUSE_SU-2018-2069-1.NASL
description	This update for xen fixes the following issues: Security issues fixed : - CVE-2018-12617: Fix integer overflow that causes segmentation fault in qmp_guest_file_read() with g_malloc() (bsc#1098744). - CVE-2018-3665: Fix Lazy FP Save/Restore issue (XSA-267) (bsc#1095242). - CVE-2018-11806: Fix heap buffer overflow while reassembling fragmented datagrams (bsc#1096224). - CVE-2018-12891: Fix possible Denial of Service (DoS) via certain PV MMU operations that affect the entire host (XSA-264) (bsc#1097521). - CVE-2018-12893: Fix crash/Denial of Service (DoS) via safety check (XSA-265) (bsc#1097522). Bug fixes : - bsc#1079730: Fix failed
last seen	2020-06-01
modified	2020-06-02
plugin id	111371
published	2018-07-27
reporter	This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/111371
title	SUSE SLES12 Security Update : xen (SUSE-SU-2018:2069-1)

NASL family	SuSE Local Security Checks
NASL id	SUSE_SU-2018-2528-1.NASL
description	This update for xen fixes the following issues: These security issue were fixed : - CVE-2018-3646: Systems with microprocessors utilizing speculative execution and address translations may have allowed unauthorized disclosure of information residing in the L1 data cache to an attacker with local user access with guest OS privilege via a terminal page fault and a side-channel analysis (bsc#1091107, bsc#1027519). - CVE-2018-12617: An integer overflow that could cause a segmentation fault in qmp_guest_file_read() with g_malloc() in qemu-guest-agent was fixed (bsc#1098744) - CVE-2018-3665: System software utilizing Lazy FP state restore technique on systems using Intel Core-based microprocessors may potentially allow a local process to infer data from another process through a speculative execution side channel. (bsc#1095242) - CVE-2018-3639: Systems with microprocessors utilizing speculative execution and speculative execution of memory reads before the addresses of all prior memory writes are known may allow unauthorized disclosure of information to an attacker with local user access via a side-channel analysis, aka Speculative Store Bypass (SSB), Variant 4. (bsc#1092631) - CVE-2017-5715: Systems with microprocessors utilizing speculative execution and indirect branch prediction may allow unauthorized disclosure of information to an attacker with local user access via a side-channel analysis. (bsc#1074562) - CVE-2017-5753: Systems with microprocessors utilizing speculative execution and branch prediction may allow unauthorized disclosure of information to an attacker with local user access via a side-channel analysis. (bsc#1074562) - CVE-2017-5754: Systems with microprocessors utilizing speculative execution and indirect branch prediction may allow unauthorized disclosure of information to an attacker with local user access via a side-channel analysis of the data cache. (bsc#1074562) - CVE-2018-12891: Certain PV MMU operations may take a long time to process. For that reason Xen explicitly checks for the need to preempt the current vCPU at certain points. A few rarely taken code paths did bypass such checks. By suitably enforcing the conditions through its own page table contents, a malicious guest may cause such bypasses to be used for an unbounded number of iterations. A malicious or buggy PV guest may cause a Denial of Service (DoS) affecting the entire host. Specifically, it may prevent use of a physical CPU for an indeterminate period of time. (bsc#1097521) - CVE-2018-12893: One of the fixes in XSA-260 added some safety checks to help prevent Xen livelocking with debug exceptions. Unfortunately, due to an oversight, at least one of these safety checks can be triggered by a guest. A malicious PV guest can crash Xen, leading to a Denial of Service. Only x86 PV guests can exploit the vulnerability. x86 HVM and PVH guests cannot exploit the vulnerability. An attacker needs to be able to control hardware debugging facilities to exploit the vulnerability, but such permissions are typically available to unprivileged users. (bsc#1097522) - CVE-2018-11806: m_cat in slirp/mbuf.c in Qemu has a heap-based buffer overflow via incoming fragmented datagrams. (bsc#1096224) - CVE-2018-10982: An issue was discovered in Xen allowed x86 HVM guest OS users to cause a denial of service (unexpectedly high interrupt number, array overrun, and hypervisor crash) or possibly gain hypervisor privileges by setting up an HPET timer to deliver interrupts in IO-APIC mode, aka vHPET interrupt injection. (bsc#1090822) - CVE-2018-10981: An issue was discovered in Xen that allowed x86 HVM guest OS users to cause a denial of service (host OS infinite loop) in situations where a QEMU device model attempts to make invalid transitions between states of a request. (bsc#1090823) Following bugs were fixed : - After updating to kernel 3.0.101-0.47.106.32-xen system crashes in check_bugs() (bsc#1097206) - bsc#1079730 - in xen-kmp, unplug emulated devices after migration This is required since xen-4.10 and/or qemu-2.10 because the state of unplug is not propagated from one dom0 to another. Without this unplug qemu
last seen	2020-06-01
modified	2020-06-02
plugin id	112147
published	2018-08-28
reporter	This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/112147
title	SUSE SLES11 Security Update : xen (SUSE-SU-2018:2528-1) (Foreshadow) (Meltdown) (Spectre)

NASL family	SuSE Local Security Checks
NASL id	SUSE_SU-2018-2081-2.NASL
description	This update for xen fixes the following issues : Security issues fixed : CVE-2018-12891: Fix preemption checks bypass in x86 PV MM handling (XSA-264) (bsc#1097521). CVE-2018-12892: Fix libxl failure to honour readonly flag on HVM emulated SCSI disks (XSA-266) (bsc#1097523). CVE-2018-12893: Fix #DB exception safety check that could be triggered by a guest (XSA-265) (bsc#1097522). CVE-2018-11806: Fix heap buffer overflow while reassembling fragmented datagrams (bsc#1096224). CVE-2018-3665: Fix lazy FP Save/Restore (XSA-267) (bsc#1095242). Bug fixes: bsc#1027519: Update to Xen 4.7.6 bug fix only release. bsc#1087289: Xen BUG at sched_credit.c:1663. bsc#1094725: `virsh blockresize` does not work with Xen qdisks. 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	2020-06-01
modified	2020-06-02
plugin id	118277
published	2018-10-22
reporter	This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/118277
title	SUSE SLES12 Security Update : xen (SUSE-SU-2018:2081-2)

NASL family	SuSE Local Security Checks
NASL id	OPENSUSE-2019-533.NASL
description	This update for xen fixes the following issues : Security issues fixed : - CVE-2018-3665: Fix Lazy FP Save/Restore issue (XSA-267) (bsc#1095242). - CVE-2018-12891: Fix possible Denial of Service (DoS) via certain PV MMU operations that affect the entire host (XSA-264) (bsc#1097521). - CVE-2018-12892: Fix libxl to honour the readonly flag on HVM emulated SCSI disks (XSA-266) (bsc#1097523). - CVE-2018-12893: Fix crash/Denial of Service (DoS) via safety check (XSA-265) (bsc#1097522). Bug fixes : - bsc#1027519: Add upstream patches from January. - bsc#1098403: Fix regression introduced by changes for bsc#1079730. A PV domU without qcow2 and/or vfb has no qemu attached. Ignore QMP errors for PV domUs to handle PV domUs with and without an attached qemu-xen. - bsc#1087289: Fix xen scheduler crash. This update was imported from the SUSE:SLE-15:Update update project.
last seen	2020-06-01
modified	2020-06-02
plugin id	123224
published	2019-03-27
reporter	This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/123224
title	openSUSE Security Update : xen (openSUSE-2019-533)

NASL family	SuSE Local Security Checks
NASL id	SUSE_SU-2018-2056-1.NASL
description	This update for xen fixes the following issues: Security issues fixed : - CVE-2018-12617: Fix integer overflow that causes segmentation fault in qmp_guest_file_read() with g_malloc() (bsc#1098744). - CVE-2018-3665: Fix Lazy FP Save/Restore issue (XSA-267) (bsc#1095242). - CVE-2018-11806: Fix heap buffer overflow while reassembling fragmented datagrams (bsc#1096224). - CVE-2018-12891: Fix possible Denial of Service (DoS) via certain PV MMU operations that affect the entire host (XSA-264) (bsc#1097521). - CVE-2018-12893: Fix crash/Denial of Service (DoS) via safety check (XSA-265) (bsc#1097522). Bug fixes : - bsc#1079730: Fix failed
last seen	2020-06-01
modified	2020-06-02
plugin id	111346
published	2018-07-26
reporter	This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/111346
title	SUSE SLES12 Security Update : xen (SUSE-SU-2018:2056-1)

NASL family	Misc.
NASL id	XEN_SERVER_XSA-265.NASL
description	According to its self-reported version number, the Xen hypervisor installed on the remote host is affected by a local denial of service vulnerability. Note that Nessus has checked the changeset versions based on the xen.git change log. Nessus did not check guest hardware configurations or if patches were applied manually to the source code before a recompile and reinstall.
last seen	2020-06-01
modified	2020-06-02
plugin id	111380
published	2018-07-27
reporter	This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/111380
title	Xen Project x86 Debug Exception Handling Local DoS (XSA-265)

NASL family	SuSE Local Security Checks
NASL id	SUSE_SU-2018-1981-1.NASL
description	This update for xen fixes the following issues: Security issues fixed : - CVE-2018-3665: Fix Lazy FP Save/Restore issue (XSA-267) (bsc#1095242). - CVE-2018-12891: Fix possible Denial of Service (DoS) via certain PV MMU operations that affect the entire host (XSA-264) (bsc#1097521). - CVE-2018-12892: Fix libxl to honour the readonly flag on HVM emulated SCSI disks (XSA-266) (bsc#1097523). - CVE-2018-12893: Fix crash/Denial of Service (DoS) via safety check (XSA-265) (bsc#1097522). Bug fixes : - bsc#1027519: Add upstream patches from January. - bsc#1098403: Fix regression introduced by changes for bsc#1079730. A PV domU without qcow2 and/or vfb has no qemu attached. Ignore QMP errors for PV domUs to handle PV domUs with and without an attached qemu-xen. - bsc#1087289: Fix xen scheduler crash. 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	2020-03-21
modified	2019-01-02
plugin id	120050
published	2019-01-02
reporter	This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/120050
title	SUSE SLED15 / SLES15 Security Update : xen (SUSE-SU-2018:1981-1)

NASL family	Misc.
NASL id	CITRIX_XENSERVER_CTX235748.NASL
description	The version of Citrix XenServer running on the remote host is missing a security hotfix. It is, therefore, affected by multiple vulnerabilities.
last seen	2020-06-01
modified	2020-06-02
plugin id	111378
published	2018-07-27
reporter	This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/111378
title	Citrix XenServer Multiple Vulnerabilities (CTX235748)

NASL family	Fedora Local Security Checks
NASL id	FEDORA_2018-A7862A75F5.NASL
description	preemption checks bypassed in x86 PV MM handling [XSA-264, CVE-2018-12891] (#1595959) x86: #DB exception safety check can be triggered by a guest [XSA-265, CVE-2018-12893] (#1595958) libxl fails to honour readonly flag on HVM emulated SCSI disks [XSA-266, CVE-2018-12892] (#1595957) 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	2020-06-05
modified	2019-01-03
plugin id	120682
published	2019-01-03
reporter	This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/120682
title	Fedora 28 : xen (2018-a7862a75f5)

NASL family	Debian Local Security Checks
NASL id	DEBIAN_DLA-1577.NASL
description	Multiple vulnerabilities have been discovered in the Xen hypervisor, which could result in denial of service, informations leaks or privilege escalation. For Debian 8
last seen	2020-06-01
modified	2020-06-02
plugin id	118892
published	2018-11-13
reporter	This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/118892
title	Debian DLA-1577-1 : xen security update

NASL family	SuSE Local Security Checks
NASL id	SUSE_SU-2018-2037-1.NASL
description	This update for xen fixes the following issues: Security issues fixed : - CVE-2018-12617: Fix integer overflow that causes segmentation fault in qmp_guest_file_read() with g_malloc() (bsc#1098744). - CVE-2018-3665: Fix Lazy FP Save/Restore issue (XSA-267) (bsc#1095242). - CVE-2018-11806: Fix heap buffer overflow while reassembling fragmented datagrams (bsc#1096224). - CVE-2018-12891: Fix possible Denial of Service (DoS) via certain PV MMU operations that affect the entire host (XSA-264) (bsc#1097521). - CVE-2018-12893: Fix crash/Denial of Service (DoS) via safety check (XSA-265) (bsc#1097522). Bug fixes : - bsc#1079730: Fix failed
last seen	2020-06-01
modified	2020-06-02
plugin id	111261
published	2018-07-24
reporter	This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/111261
title	SUSE SLES11 Security Update : xen (SUSE-SU-2018:2037-1)

NASL family	Debian Local Security Checks
NASL id	DEBIAN_DSA-4236.NASL
description	Multiple vulnerabilities have been discovered in the Xen hypervisor : - CVE-2018-12891 It was discovered that insufficient validation of PV MMU operations may result in denial of service. - CVE-2018-12892 It was discovered that libxl fails to honour the
last seen	2020-06-01
modified	2020-06-02
plugin id	110787
published	2018-06-29
reporter	This script is Copyright (C) 2018 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/110787
title	Debian DSA-4236-1 : xen - security update

NASL family	Gentoo Local Security Checks
NASL id	GENTOO_GLSA-201810-06.NASL
description	The remote host is affected by the vulnerability described in GLSA-201810-06 (Xen: Multiple vulnerabilities) Multiple vulnerabilities have been discovered in Xen. Please review the referenced CVE identifiers for details. Impact : A local attacker could cause a Denial of Service condition or disclose sensitive information. Workaround : There is no known workaround at this time.
last seen	2020-06-01
modified	2020-06-02
plugin id	118506
published	2018-10-31
reporter	This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/118506
title	GLSA-201810-06 : Xen: Multiple vulnerabilities (Foreshadow) (Meltdown) (Spectre)

NASL family	SuSE Local Security Checks
NASL id	OPENSUSE-2018-766.NASL
description	This update for xen fixes the following issues : Security issues fixed : - CVE-2018-3665: Fix Lazy FP Save/Restore issue (XSA-267) (bsc#1095242). - CVE-2018-12891: Fix possible Denial of Service (DoS) via certain PV MMU operations that affect the entire host (XSA-264) (bsc#1097521). - CVE-2018-12892: Fix libxl to honour the readonly flag on HVM emulated SCSI disks (XSA-266) (bsc#1097523). - CVE-2018-12893: Fix crash/Denial of Service (DoS) via safety check (XSA-265) (bsc#1097522). Bug fixes : - bsc#1027519: Add upstream patches from January. - bsc#1098403: Fix regression introduced by changes for bsc#1079730. A PV domU without qcow2 and/or vfb has no qemu attached. Ignore QMP errors for PV domUs to handle PV domUs with and without an attached qemu-xen. - bsc#1087289: Fix xen scheduler crash. This update was imported from the SUSE:SLE-15:Update update project.
last seen	2020-06-05
modified	2018-07-30
plugin id	111418
published	2018-07-30
reporter	This script is Copyright (C) 2018-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
source	https://www.tenable.com/plugins/nessus/111418
title	openSUSE Security Update : xen (openSUSE-2018-766)

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Summary

Vulnerable Configurations

Nessus

References

Vulnerabilities > CVE-2018-12893