CVE-2026-55999
xorg-server / xwayland glamor font atlas Heap Buffer Overflow
Description
Local attackers with a X connection able to provide PCX fonts to the X server xorg-server before 21.2.24 and xwayland before 24.1.13 could cause a heap buffer overflow via SetFont due to missing glyph boundary checks.
INFO
Published Date :
July 8, 2026, 9:16 a.m.
Last Modified :
July 8, 2026, 9:16 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | 404e59f5-483d-4b8a-8e7a-e67604dd8afb | ||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update xorg-server to version 21.2.24 or later.
- Update xwayland to version 24.1.13 or later.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-55999.
| URL | Resource |
|---|---|
| https://gitlab.freedesktop.org/xorg/xserver/-/commit/fbf7bac22e2c6bd627fb042742a23318263edae1 | |
| https://www.openwall.com/lists/oss-security/2026/07/08/2 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-55999 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-55999
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-55999 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-55999 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Jul. 08, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://gitlab.freedesktop.org/xorg/xserver/', 'vendor': 'X.Org', 'product': 'xorg-server', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '21.1.24', 'versionType': 'rpm'}], 'packageName': 'xorg-server', 'defaultStatus': 'unaffected'}, {'repo': 'https://gitlab.freedesktop.org/xorg/xserver/', 'vendor': 'X.Org', 'product': 'xwayland', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '24.1.13', 'versionType': 'rpm'}], 'packageName': 'xwayland', 'defaultStatus': 'unaffected'}] Added Description Local attackers with a X connection able to provide PCX fonts to the X server xorg-server before 21.2.24 and xwayland before 24.1.13 could cause a heap buffer overflow via SetFont due to missing glyph boundary checks. Added CVSS V3.1 AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H Added CWE CWE-122 Added Reference https://gitlab.freedesktop.org/xorg/xserver/-/commit/fbf7bac22e2c6bd627fb042742a23318263edae1 Added Reference https://www.openwall.com/lists/oss-security/2026/07/08/2