CVE-2026-54692 SAIL: XBM X10 decoder writes 2 bytes per literal into a 1-byte-per-literal buffer (heap out-of-bounds write)
Heap out-of-bounds write in SAIL image library allows attackers to execute code or crash applications via malicious XBM files.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-54692?
CVE-2026-54692 is a high-severity memory corruption vulnerability in HappySeaFox sail, published on 17 Sep 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
SAIL is a cross-platform library for loading and saving images with support for animation, metadata, and ICC profiles. Prior to 1.0.0, sail_codec_load_frame_v8_xbm() in src/sail-codecs/xbm/xbm.c allocates the decoded pixel buffer using the X11 one-byte-per-literal layout, but an X10 static short file causes the flat decode loop to write two file-controlled bytes per literal. When ceil(width/8) produces an odd row stride, the X10 literal count includes a padding byte for every row, but the destination has no space for those bytes, so loading the XBM through sail_load_from_file, sail_load_from_memory, or sail_start_loading_* produces a forward heap overwrite that scales with image height. The X11 static char path is not affected. The overwrite can corrupt process state, cause reliable crashes, and potentially enable code execution in a susceptible consuming application. This issue is fixed in version 1.0.0.
Which versions are affected by CVE-2026-54692?
How do I fix CVE-2026-54692?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-54692 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54692 exists.
Sources
Also known as DEBIAN-CVE-2026-54692, GHSA-gp27-qv2x-55v5, UBUNTU-CVE-2026-54692.