CVE-2026-50262
Description
An out-of-bounds read flaw was found in the X.Org X server and Xwayland in __glXDisp_ChangeDrawableAttributes(). A wrong size validation check can read a client-controlled number of bytes, exceeding the request buffer, leading to information disclosure. A write path also exists but requires byte-swapped clients which is disabled by default.
Statement
Red Hat rates this issue as Moderate impact. In xorg-x11-server and xorg-x11-server-Xwayland, __glXDisp_ChangeDrawableAttributes() validates request size incorrectly, allowing a local X client to read bytes beyond the GLX request buffer—information disclosure. An out-of-bounds write path also exists but requires byte-swapped clients, which is disabled by default on Red Hat builds. Any local user who can connect to the X server display can trigger the read path. Upstream fixed this in xorg-server 21.1.23 and xwayland 24.1.12.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | 5.5 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | None | N/A | None |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Red Hat CVSS v3 Score Explanation
ZDI-suggested score (5.5) for OOB read path, not verified by xorg security team.
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
An attacker could get secret values such as cryptographic keys, PII, memory addresses, or other information that could be used in additional attacks.
Confidentiality
Technical Impact: Bypass Protection Mechanism
Out-of-bounds memory could contain memory addresses or other information that can be used to bypass ASLR and other protection mechanisms in order to improve the reliability of exploiting a separate weakness for code execution.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An attacker could cause a segmentation fault or crash by causing memory to be read outside of the bounds of the buffer. This is especially likely when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string.
Other
Technical Impact: Varies by Context
The read operation could produce other undefined or unexpected results.
Acknowledgements
Upstream acknowledges Anonymous (Trend Micro Zero Day Initiative) as the original reporter.
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