Buffer overflow in X.org Xorg-Server
CVE-2026-55999
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.
Vulnerability class: Buffer Overflow
EPSS: 0.003 (19.2th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.5 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H.
Affected products
- X.org Xorg-server — versions 0
- X.org X_server
- X.org Xwayland — versions 0
Weakness classification (CWE)
References
- meissner@suse.de (Patch, patch)
- meissner@suse.de (vendor-advisory, Patch, Mailing List, Third Party Advisory)
Frequently asked questions
- What is CVE-2026-55999?
- CVE-2026-55999 is a high-severity vulnerability in X.org Xorg-Server, classified under Heap-based Buffer Overflow. CVSS score: 8.5/10. Published 2026-07-08.
- How severe is CVE-2026-55999?
- High severity. CVSS v3 base score is 8.5 out of 10.