CVE-2026-112398: Heap Overflow

Description

Pillow is a Python imaging library. Prior to 13.0.0, Pillow's FlashPix JPEG-tile decoder can write decoded scanlines beyond the allocated tile buffer. FlashPix (FPX) JPEG decoding selects raw mode LA with two bytes per pixel, while an unrecognized JPEG mode can be decoded as JCS_UNKNOWN with four components, causing ImagingJpegDecode to write four-component scanlines into the two-byte tile buffer. An attacker can supply a crafted OLE2 FlashPix file to an application with the optional olefile dependency installed that opens or thumbnails untrusted input. This can corrupt heap memory and may allow arbitrary code execution. This issue is fixed in version 13.0.0.

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Weakness Type (CWE)

CWE-122 CWE-122

CWE-787 Out-of-bounds Write

References

Other References

https://github.com/python-pillow/Pillow/commit/242a059aedc1935097d9aa1dc3f099750467ba75 https://github.com/python-pillow/Pillow/releases/tag/13.0.0 https://github.com/python-pillow/Pillow/security/advisories/GHSA-5x8w-8jj5-q52h

Frequently Asked Questions

What is CVE-2026-112398? +

Pillow is a Python imaging library. Prior to 13.0.0, Pillow's FlashPix JPEG-tile decoder can write decoded scanlines beyond the allocated tile buffer. FlashPix (FPX) JPEG decoding selects raw mode LA with two bytes per pixel, while an unrecognized JPEG mode can be decoded as JCS_UNKNOWN with four components, causing ImagingJpegDecode to write four-component scanlines into the two-byte tile buffer. An attacker can supply a crafted OLE2 FlashPix file to an application with the optional olefile dependency installed that opens or thumbnails untrusted input. This can corrupt heap memory and may allow arbitrary code execution. This issue is fixed in version 13.0.0.

How do I check if I'm vulnerable to CVE-2026-112398? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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