CVE-2026-40492: Happyseafox Sail

Critical severity, CVSS 9.8. EPSS: 0.6% chance of exploitation in the next 30 days.

SAIL is a cross-platform library for loading and saving images with support for animation, metadata, and ICC profiles. Prior to commit 36aa5c7ec8a2bb35f6fb867a1177a6f141156b02, the XWD codec resolves pixel format based on `pixmap_depth` but the byte-swap code uses `bits_per_pixel` independently. When `pixmap_depth=8` (BPP8_INDEXED, 1 byte/pixel buffer) but `bits_per_pixel=32`, the byte-swap loop accesses memory as `uint32_t*`, reading/writing 4x the allocated buffer size. This is a different vulnerability from the previously reported GHSA-3g38-x2pj-mv55 (CVE-2026-27168), which addressed `bytes_per_line` validation. Commit 36aa5c7ec8a2bb35f6fb867a1177a6f141156b02 contains a patch.

Affected products

• Happyseafox Sail: before 36aa5c7ec8a2bb35f6fb867a1177a6f141156b02 (fixed in 36aa5c7ec8a2bb35f6fb867a1177a6f141156b02)

Published 2026-04-18. Last modified 2026-06-17.