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CVE-2026-44950 on Cyberus Linux 26.05

Aliases: CVE-2026-44950

Packages: libxfont_2

Status: Resolved

Advisory Information

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.

Updates

2026-09-03 23:08 CEST

Metadata changes:

  • Status for package libxfont_2: “Resolved” (c418cc929b3e42958856c17507e3206f2d948de8)

2026-08-12 17:27 CEST

Metadata changes:

  • Status for package libxfont_2: “In Progress” (c418cc929b3e42958856c17507e3206f2d948de8)

2026-08-07 10:30 CEST

Metadata changes:

  • Status for package libxfont_2: “Plausible”

(Amended on: 2026-08-11 03:11 CEST)