HappySeaFox sail Field Header out-of-bounds write

Summaryinfo

A vulnerability, which was classified as critical, has been found in HappySeaFox sail. This vulnerability affects unknown code of the component Field Handler. The manipulation of the argument Header leads to out-of-bounds write. This vulnerability is listed as CVE-2026-40493. The attack may be initiated remotely. There is no available exploit. To fix this issue, it is recommended to deploy a patch.

Detailsinfo

A vulnerability was found in HappySeaFox sail (affected version unknown). It has been rated as critical. This issue affects an unknown functionality of the component Field Handler. The manipulation of the argument Header with an unknown input leads to a out-of-bounds write vulnerability. Using CWE to declare the problem leads to CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

SAIL is a cross-platform library for loading and saving images with support for animation, metadata, and ICC profiles. Prior to commit c930284445ea3ff94451ccd7a57c999eca3bc979, the PSD codec computes bytes-per-pixel (`bpp`) from raw header fields `channels * depth`, but the pixel buffer is allocated based on the resolved pixel format. For LAB mode with `channels=3, depth=16`, `bpp = (3*16+7)/8 = 6`, but the format `BPP40_CIE_LAB` allocates only 5 bytes per pixel. Every pixel write overshoots, causing a deterministic heap buffer overflow on every row. Commit c930284445ea3ff94451ccd7a57c999eca3bc979 contains a patch.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-40493 since 04/13/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit.

Applying the patch c930284445ea3ff94451ccd7a57c999eca3bc979 is able to eliminate this problem. The bugfix is ready for download at github.com.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-23646). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• HappySeaFox

Name

• sail

License

• open-source

Website

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

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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