SAIL has heap buffer overflow in XWD decoder — bits_per_pixel vs pixmap_depth type confusion in byte-swap

published 2026-04-18 6 mo ago modified 2026-10-26 13 d ago also EUVD-2026-23644

cvss: 9.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 35%
public exploits: 0; none known

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.

Patch / fix

fixed in 1 distros 1 links 1

sail sail 36aa5c7ec8a2bb35f6fb867a1177a6f141156b02

sail Debian 14 0.9.10-2

debian advisories DEBIAN-CVE-2026-40492

github.com/HappySeaFox/sail@36aa5c7 commit

CISA SSVC

Exploitation: Proof of concept is public
Automatable: yes
Technical impact: total
Assessed: 6 mo ago (2026-04-20)

Exploit prediction

0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/HappySeaFox/sail/security/advisories/GHSA-526v-vm72-4v64 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

HappySeaFox sail

Classification

Weakness

CWE-787 Out-of-bounds Write

References

Sources

CVE List CVE-2026-40492
NVD CVE-2026-40492

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary