Vulnerabilities > CVE-2023-41349 - Use of Externally-Controlled Format String vulnerability in Asus Rt-Ax88U Firmware

Attack vector
Attack complexity
Privileges required
Confidentiality impact
Integrity impact
Availability impact
low complexity


ASUS router RT-AX88U has a vulnerability of using externally controllable format strings within its Advanced Open VPN function. An authenticated remote attacker can exploit the exported OpenVPN configuration to execute an externally-controlled format string attack, resulting in sensitivity information leakage, or forcing the device to reset and permanent denial of service.

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Format String Injection
    An attacker includes formatting characters in a string input field on the target application. Most applications assume that users will provide static text and may respond unpredictably to the presence of formatting character. For example, in certain functions of the C programming languages such as printf, the formatting character %s will print the contents of a memory location expecting this location to identify a string and the formatting character %n prints the number of DWORD written in the memory. An attacker can use this to read or write to memory locations or files, or simply to manipulate the value of the resulting text in unexpected ways. Reading or writing memory may result in program crashes and writing memory could result in the execution of arbitrary code if the attacker can write to the program stack.
  • String Format Overflow in syslog()
    This attack targets the format string vulnerabilities in the syslog() function. An attacker would typically inject malicious input in the format string parameter of the syslog function. This is a common problem, and many public vulnerabilities and associated exploits have been posted.