CVE-2026-93520
Description
A flaw was found in xorg-x11-server. In the X Keyboard Extension (XKB), key name memory is allocated with an insufficient buffer size compared to the maximum supported range. An authenticated local client can exploit this flaw by sending requests that modify the keycode range, triggering a heap-based buffer overflow. This vulnerability can lead to arbitrary code execution or cause a Denial of Service (DoS) by crashing the X server.
Statement
This vulnerability is rated as having a Moderate severity for Red Hat Enterprise Linux because exploitation requires an established, authenticated connection from a client session to the local display server. Under typical enterprise deployments, Xorg and Xwayland do not listen for unauthenticated network traffic by default, restricting potential attacks to authenticated local users or forwarded sessions. Although a successful exploit may cause memory corruption leading to server crashes or arbitrary code execution within the privileges of the running display server, it cannot be triggered remotely by unauthenticated attackers.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.8 | N/A | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | High | N/A | N/A |
| Integrity Impact | High | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Write operations could cause memory corruption. In some cases, an adversary can modify control data such as return addresses in order to execute unexpected code.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
Attempting to access out-of-range, invalid, or unauthorized memory could cause the product to crash.
Other
Technical Impact: Unexpected State
Subsequent write operations can produce undefined or unexpected results.
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