🛡️ CVE-2026-56003 on Ubuntu — libxfont

⚪ Unknown ✅ No Known Exploit OSV

N/A

CVSS Score

0 Low4 Medium7 High9 Critical10

Description

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.

Distribution advisory

This page covers CVE-2026-56003 as tracked by Ubuntu, for the package libxfont. The fix is available in version 1:2.0.6-2ubuntu0.2; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

Weakness class

UBUNTU-CVE-2026-56003 is classified as CWE-122: Heap-based Buffer Overflow. A write past the end of a heap allocation corrupts allocator metadata or neighbouring objects.

Affected software

UBUNTU-CVE-2026-56003 is recorded against 2 packages.

libxfont (fixed in 1:2.0.6-2ubuntu0.2)
libxfont2

Timeline and source

Published on 8 July 2026 and last revised on 21 July 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

ubuntu.com (Report)
www.cve.org (Report)
www.openwall.com (Report)
ubuntu.com (Advisory)

Details

Severity Unknown

CVSS Score N/A

CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CWE N/A

Public Exploit ✅ No

Source OSV

Published 2026-07-08

Updated 2026-08-12

Modified 2026-07-21

Fix URL N/A

Affected Packages

Software	From version	Fixed in
libxfont	—	1:2.0.6-2ubuntu0.2
libxfont2	—	—

References

REPORT https://ubuntu.com/security/CVE-2026-56003

REPORT https://www.cve.org/CVERecord?id=CVE-2026-56003

REPORT https://www.openwall.com/lists/oss-security/2026/07/08/1

ADVISORY https://ubuntu.com/security/notices/USN-8560-1

🔗 NVD 🔗 Mitre

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