RHEL 6/7/8/9 X.org X11 Server/TigerVNC: heap-based buffer overflow (CVE-2025-26597) #shorts

Summary

In today's episode, we're diving into CVE-2025-26597, a newly discovered vulnerability affecting Red Hat Enterprise Linux and certain X.Org and Xwayland products. This vulnerability is categorized as a heap-based buffer overflow, which can have serious security implications if not addressed.

Product details

The products affected by CVE-2025-26597 include Red Hat Enterprise Linux versions 6, 7, 8, and 9. This vulnerability is specifically found within the X.Org and Xwayland components of these systems, impacting their ability to handle certain key-symptoms tables.

Vulnerability type summary

This vulnerability is classified as a heap-based buffer overflow. Essentially, a buffer overflow occurs when more data is written to a buffer than it can hold, which can lead to various types of unexpected and potentially dangerous behaviors.

Details of the vulnerability

The vulnerability arises when XkbChangeTypesOfKey() is called with an argument of zero groups, causing the key symbols table to resize to zero while leaving the key actions unchanged. If the function is then called again with a non-zero group, it leads to a buffer overflow because the key actions do not match the expected size. This flaw could be exploited to execute arbitrary code or crash the system.

Conclusion

To mitigate the risks associated with CVE-2025-26597, users of the affected versions of Red Hat Enterprise Linux should apply security updates from providers like SUSE, which has already released advisories and updates. Keeping systems updated is crucial in protecting against potential exploits that may arise from such vulnerabilities.

Watch the full video on YouTube: CVE-2025-26597

Remediation and exploitation details

This chain involves the following actors

This following systems are involved

Attack entry point

Remediation actions

Exploitation actions

CVE database technical details

CVE ID

CVE-2025-26597

Description

A buffer overflow flaw was found in X.Org and Xwayland. If XkbChangeTypesOfKey() is called with a 0 group, it will resize the key symbols table to 0 but leave the key actions unchanged. If the same function is later called with a non-zero value of groups, this will cause a buffer overflow because the key actions are of the wrong size.

Provider

redhat

CWE / problem types

Improper Restriction of Operations within the Bounds of a Memory Buffer

Affected Software Versions

None:None:[{'status': 'affected', 'version': '0', 'lessThan': '21.1.16', 'versionType': 'semver'}, {'status': 'affected', 'version': '22.0.0', 'lessThan': '24.1.6', 'versionType': 'semver'}],Red Hat:Red Hat Enterprise Linux 7 Extended Lifecycle Support:[{'version': '0:1.8.0-36.el7_9', 'lessThan': '*', 'versionType': 'rpm', 'status': 'unaffected'}],Red Hat:Red Hat Enterprise Linux 7 Extended Lifecycle Support:[{'version': '0:1.20.4-30.el7_9', 'lessThan': '*', 'versionType': 'rpm', 'status': 'unaffected'}],Red Hat:Red Hat Enterprise Linux 8:[{'version': '0:1.13.1-15.el8_10', 'lessThan': '*', 'versionType': 'rpm', 'status': 'unaffected'}],Red Hat:Red Hat Enterprise Linux 8.2 Advanced Update Support:[{'version': '0:1.9.0-15.el8_2.13', 'lessThan': '*', 'versionType': 'rpm', 'status': 'unaffected'}],Red Hat:Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support:[{'version': '0:1.11.0-8.el8_4.12', 'lessThan': '*', 'versionType': 'rpm', 'status': 'unaffected'}],Red Hat:Red Hat Enterprise Linux 8.4 Telecommunications Update Service:[{'version': '0:1.11.0-8.el8_4.12', 'lessThan': '*', 'versionType': 'rpm', 'status': 'unaffected'}],Red Hat:Red Hat Enterprise Linux 8.4 Update Services for SAP Solutions:[{'version': '0:1.11.0-8.el8_4.12', 'lessThan': '*', 'versionType': 'rpm', 'status': 'unaffected'}],Red Hat:Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support:[{'version': '0:1.12.0-6.el8_6.13', 'lessThan': '*', 'versionType': 'rpm', 'status': 'unaffected'}],Red Hat:Red Hat Enterprise Linux 8.6 Telecommunications Update Service:[{'version': '0:1.12.0-6.el8_6.13', 'lessThan': '*', 'versionType': 'rpm', 'status': 'unaffected'}],Red Hat:Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions:[{'version': '0:1.12.0-6.el8_6.13', 'lessThan': '*', 'versionType': 'rpm', 'status': 'unaffected'}],Red Hat:Red Hat Enterprise Linux 8.8 Extended Update Support:[{'version': '0:1.12.0-15.el8_8.12', 'lessThan': '*', 'versionType': 'rpm', 'status': 'unaffected'}],Red Hat:Red Hat Enterprise Linux 9:[{'version': '0:1.14.1-1.el9_5.1', 'lessThan': '*', 'versionType': 'rpm', 'status': 'unaffected'}],Red Hat:Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions:[{'version': '0:1.11.0-22.el9_0.13', 'lessThan': '*', 'versionType': 'rpm', 'status': 'unaffected'}],Red Hat:Red Hat Enterprise Linux 9.2 Extended Update Support:[{'version': '0:1.12.0-14.el9_2.10', 'lessThan': '*', 'versionType': 'rpm', 'status': 'unaffected'}],Red Hat:Red Hat Enterprise Linux 9.4 Extended Update Support:[{'version': '0:1.13.1-8.el9_4.5', 'lessThan': '*', 'versionType': 'rpm', 'status': 'unaffected'}],Red Hat:Red Hat Enterprise Linux 6:None,Red Hat:Red Hat Enterprise Linux 6:None,Red Hat:Red Hat Enterprise Linux 8:None,Red Hat:Red Hat Enterprise Linux 8:None,Red Hat:Red Hat Enterprise Linux 9:None,Red Hat:Red Hat Enterprise Linux 9:None

Date Published

2025-02-25T15:54:48.196Z

Last Updated

2025-04-14T19:34:29.202Z