Buffer Overflow Affecting libXfont2-debugsource package, versions <0:2.0.7-1.amzn2023.0.3


Severity

Recommended
0.0
high
0
10

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.44% (37th percentile)

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  • Snyk IDSNYK-AMZN2023-LIBXFONT2DEBUGSOURCE-19476704
  • published1 Sept 2026
  • disclosed10 Sept 2026

Introduced: 1 Sep 2026

NewCVE-2026-44950  (opens in a new tab)
CWE-120  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 libXfont2-debugsource to version 0:2.0.7-1.amzn2023.0.3 or higher.
This issue was patched in ALAS2023-2026-2112.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libXfont2-debugsource package and not the libXfont2-debugsource package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

fs_read_glyphs() in the libXfont2 font-server client (src/fc/fserve.c) copies each glyph's bitmap into a single buffer. Existing checks validates only that the source slice (position, length) lies within the source bitmap buffer. It does not check whether the running destination cursor has exceeded the allocation.

A malicious font server can send overlapping source offsets -- for example 1000 glyphs each referencing {position:0, length:64} with nbytes=64. Each individual source range passes the existing validation, but the cumulative writes total 64000 bytes into a 64-byte destination buffer. This is a heap buffer overflow with attacker-controlled content.

CVSS Base Scores

version 3.1