Out-of-bounds Read Affecting libXfont2 package, versions <0:2.0.3-12.el9_6.3


Severity

Recommended
0.0
high
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.26% (17th percentile)

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  • Snyk IDSNYK-RHEL9-LIBXFONT2-19723071
  • published13 Sept 2026
  • disclosed5 Aug 2026

Introduced: 5 Aug 2026

CVE-2026-59679  (opens in a new tab)
CWE-125  (opens in a new tab)

How to fix?

Upgrade RHEL:9 libXfont2 to version 0:2.0.3-12.el9_6.3 or higher.
This issue was patched in RHSA-2026:61390.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libXfont2 package and not the libXfont2 package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

fs_read_glyphs() in the libXfont2 font-server client (src/fc/fserve.c) indexes the per-character encoding[] array using num_chars from the FS_QueryXBitmaps16 reply, but that array was allocated with a size derived from num_extents in the separate FS_QueryXExtents16 reply. The two CARD32 fields are never cross-checked. A malicious or compromised font server can send a small num_extents (e.g. 1) in the extents reply, then a large num_chars (e.g. 100000) in the bitmaps reply. This causes attacker-controlled out-of-bounds heap read and writes.

CVSS Base Scores

version 3.1