Buffer overflow in X Libxfont
CVE-2026-56003
A heap buffer overflow due to missing size checking in the property buffer when parsing PCF files in libXfont2 ComputeScaledProperties() before libXfont2 before 2.0.8 could be used by attackers using authenticated X clients to execute code within the X server.
Vulnerability class: Buffer Overflow
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.006 (47.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 48th percentile — 47.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.006 · change: +0.002
Affected products
- X Libxfont
- X.org Libxfont2 — versions 0
Weakness classification (CWE)
References
- www.openwall.com/lists/oss-security/2026/07/08/1 (vendor-advisory, Patch, Mailing List, Third Party Advisory)
- gitlab.freedesktop.org/xorg/lib/libxfont/-/commit/dff957a5158da038a282a59a31fe7… (Patch, patch)
Frequently asked questions
- What is CVE-2026-56003?
- CVE-2026-56003 is a high-severity vulnerability in X Libxfont, classified under Heap-based Buffer Overflow. CVSS score: 8.5/10. Published 2026-07-08.
- How severe is CVE-2026-56003?
- High severity. CVSS v3 base score is 8.5 out of 10.