CVEvulnerability

CVE-2026-59679

9.2 CRITICAL Published 2026-09-10 Modified 2026-09-10 Official page ↗
Status
Awaiting Analysis
Published
2026-09-10
Last modified
2026-09-10
Assigner
[email protected]
CVSS 4.0 ([email protected])
9.2 CRITICAL — CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1 ([email protected])
9.0 CRITICAL — CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Weaknesses
CWE-787

Description

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.

Related

Weakness · CWE (1)

  • CWE-787 Out-of-bounds Write weakness

References