CVE-2026-59959 SAIL: WebP decoder division by zero through malformed animated canvas metadata
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-59959?
CVE-2026-59959 is a medium-severity vulnerability in HappySeaFox sail, published on 28 Oct 2026.
Official description
SAIL is a cross-platform library for loading and saving images with support for animation, metadata, and ICC profiles. Prior to version 1.0.2, the built-in WebP decoder can crash during loader initialization when processing a malformed animated WebP file with inconsistent container or `ANMF` frame metadata. In `sail_codec_load_init_v8_webp()` in `src/sail-codecs/webp/webp.c`, `WebPDemuxGetI` with `WEBP_FF_CANVAS_WIDTH` can return a zero `image_local->width`, which is then used as a divisor when calculating `bytes_per_pixel` from the image row size. The division happens before frame decoding and before generic image skeleton validation in `src/sail/sail_advanced.c`, causing an arithmetic fault and process termination. Applications accepting untrusted WebP images can consequently suffer denial of service; builds must include the affected WebP codec. This issue is fixed in version 1.0.2.
Weakness: CWE-369
Which versions are affected by CVE-2026-59959?
How do I fix CVE-2026-59959?
Upgrade to a fixed version.
Is CVE-2026-59959 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-59959 exists.
Sources
Also known as DEBIAN-CVE-2026-59959, GHSA-5g8g-g347-84m8.