HappySeaFox sail XWD Codec pixmap_depth out-of-bounds write

Summaryinfo

A vulnerability classified as critical was found in HappySeaFox sail. This affects the function pixmap_depth of the component XWD Codec. Executing a manipulation can lead to out-of-bounds write. This vulnerability is tracked as CVE-2026-40492. The attack can be launched remotely. No exploit exists. A patch should be applied to remediate this issue.

Detailsinfo

A vulnerability was found in HappySeaFox sail (version unknown). It has been declared as critical. This vulnerability affects the function pixmap_depth of the component XWD Codec. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. The CWE definition for the vulnerability is CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability was named CVE-2026-40492 since 04/13/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 307449 (Linux Distros Unpatched Vulnerability : CVE-2026-40492), which helps to determine the existence of the flaw in a target environment.

Applying the patch 36aa5c7ec8a2bb35f6fb867a1177a6f141156b02 is able to eliminate this problem. The bugfix is ready for download at github.com.

The vulnerability is also documented in the databases at Tenable (307449) and EUVD (EUVD-2026-23644). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Vendor

• HappySeaFox

Name

• sail

License

• open-source

Website

• Product: https://github.com/HappySeaFox/sail/

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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