What’s Vulnerable › Vulnerabilities

CVE-2026-59679: fs_read_glyphs() heap OOB read/write via encoding array index mismatch in libXfont2

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.

Affected products

How to fix

Upgrade to a fixed version: SUSE Container suse/kiosk/tigervnc-x11vnc:1.14-63.8 2.0.3-150000.3.6.1; SUSE Container suse/kiosk/xorg:21.1-83.7 2.0.3-150000.3.6.1; SUSE Image SLES-SAP-Azure 2.0.7-160000.5.1; SUSE Image SLES-SAP-Azure-3P 2.0.7-160000.5.1; SUSE Image SLES-SAP-BYOS-Azure 2.0.7-160000.5.1; SUSE Image SLES-SAP-BYOS-EC2 2.0.7-160000.5.1; SUSE Image SLES-SAP-BYOS-GCE 2.0.7-160000.5.1; SUSE Image SLES-SAP-GCE 2.0.7-160000.5.1; SUSE Image SLES-SAP-GCE-3P 2.0.7-160000.5.1; SUSE Image SLES-SAPCAL-GCE 2.0.7-160000.5.1; SUSE Image SLES12-SP5-Azure-SAP-BYOS 2.0.3-3.6.1; SUSE Image SLES12-SP5-Azure-SAP-On-Demand 2.0.3-3.6.1. Check the vendor advisory for mitigations.

References

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