Critical Vulnerability in libX11: Remote Code Execution Risk
Summary
ALPINE-CVE-2021-31535: LookupCol.c in X.Org X through X11R7.7 and libX11 before 1.7.1 might allow remote attackers to execute arbitrary code. Affects libx11 versions < 1.6.12-r1. Fixed in 1.6.12-r1. How to fix ↓
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Background
libX11 is a core library for the X Window System, providing essential functions for managing windows and user input in graphical environments. It facilitates communication between client applications and the X server, enabling graphical user interfaces on Unix-like operating systems. The library is widely used in various applications, making it a critical component in many systems. However, it is susceptible to vulnerabilities that can be exploited by attackers, particularly those that allow remote code execution.
Vulnerability Detail
The vulnerability identified as CVE-2021-31535 exists in the XLookupColor request of libX11, which is designed for server-side color lookup. An attacker can exploit this flaw by sending color-name requests that exceed the maximum size allowed by the protocol. This excessive data can be interpreted by the server as additional X protocol requests, potentially leading to arbitrary code execution. If a victim encounters malicious terminal control sequences for color codes, the attacker may gain full control over the victim's graphical session, posing a significant security risk.
How To Fix
Minimum fixed version
1.6.12-r1
This is the first release that contains the fix.
sudo apk add --upgrade libx11Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users can limit access to the X server or implement stricter authorization controls to mitigate the risk of exploitation until the package can be updated.
Conclusion
The CVE-2021-31535 vulnerability in libX11 poses a significant risk of remote code execution, affecting numerous systems that rely on this library. Users are urged to update their libX11 packages to the latest patched versions to safeguard against potential exploits. Regular monitoring and updates are crucial in maintaining system security.
See every vulnerability recorded for libx11 →
FAQ
CVE-2021-31535 is a critical vulnerability in the libX11 library that allows remote attackers to execute arbitrary code by exploiting the XLookupColor request.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
The CVSS score for this vulnerability is 9.8, indicating a critical level of risk.
Exploitation of this vulnerability can lead to remote code execution, allowing attackers to take full control of the affected graphical session.
It is recommended to regularly check for updates and apply them promptly to mitigate the risk of vulnerabilities in your software.
References
Related vulnerabilities
Recent vulnerabilities recorded for libx11.
