Divide By Zero Affecting sail package, versions <1.2.0-1

Note: Versions mentioned in the description apply only to the upstream sail package and not the sail package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

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.

• https://security-tracker.debian.org/tracker/CVE-2026-59959
• https://github.com/HappySeaFox/sail/commit/495660135a4c62e416a1b357a4381dd30069229d
• https://github.com/HappySeaFox/sail/security/advisories/GHSA-5g8g-g347-84m8
• https://github.com/HappySeaFox/sail/tree/v1.0.2