CVE-2026-55999
Last modified
CVE-2026-55999 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. 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.. EPSS estimates a 0.28% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| X.Org | X Server | < 21.2.24 |
| X.Org | Xwayland | < 24.1.13 |
References
- https://www.openwall.com/lists/oss-security/2026/07/08/2Mailing List, Patch, Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-55999?
How severe is CVE-2026-55999?
How do I fix CVE-2026-55999?
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
Related CVEs from 2026
- CVE-2026-55993Improper Input Validation, Exposure of Sensitive Information…7.5
- CVE-2026-55994Improper Input Validation, Exposure of Sensitive Information…7.5
- CVE-2026-55995A Double Free vulnerability in open-iscsi allows an unauthen…8.7
- CVE-2026-55996A denial-of-service vulnerability was identified in multiple…4.3
- CVE-2026-55997Rancher issues long-lived registration tokens to authenticat…8.8
- CVE-2026-55998The endpoint /v3/import/{token}_{clusterId}.yaml retrieves t…5.3
- CVE-2026-5600A new API endpoint introduced in pretix 2025 that is suppose…4.3
- CVE-2026-56000Local attackers with a X connection able to provide GLX comm…7.8
- CVE-2026-56001A heap buffer overflow in BitmapScaleBitmaps in libXfont2 be…8.8
- CVE-2026-56002A heap bufferflow in pcfReadFont() due to missing glyph boun…8.8
- CVE-2026-56003A heap buffer overflow due to missing size checking in the p…8.8
- CVE-2026-56004A shellcode injection in the mercurial handler of the obs ta…10
Are you affected by CVE-2026-55999?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST