python-pillow Pillow up to 12.x PILfont src/_imaging.c integer overflow

Summaryinfo

A vulnerability classified as problematic was found in python-pillow Pillow up to 12.x. This affects an unknown part of the file src/_imaging.c of the component PILfont. The manipulation results in integer overflow. This vulnerability was named CVE-2026-96641. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as problematic has been found in python-pillow Pillow up to 12.x. Affected is an unknown function of the file src/_imaging.c of the component PILfont. The manipulation with an unknown input leads to a integer overflow vulnerability. CWE is classifying the issue as CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. This is going to have an impact on availability. CVE summarizes:

Pillow is a Python imaging library. Prior to 13.0.0, PILfont text-width accumulation in src/_imaging.c checks positive glyph advances against INT_MAX but does not check negative advances against INT_MIN. Repeating a signed 16-bit advance of -32768 can therefore execute a signed C integer overflow in xsize += dx, producing a large positive width from a negative mathematical result. Applications that use getlength(), getsize(), or derived layout, quota, serialization, or allocation calculations can experience logic-integrity errors or resource consumption, while the high-level mask path commonly retains a decompression-bomb check. This issue is fixed in version 13.0.0.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-96641 since 09/23/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit.

Upgrading to version 13.0.0 eliminates this vulnerability.

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Productinfo

Type

• Programming Language Software

Vendor

• python-pillow

Name

• Pillow

Version

• 12.x

License

• open-source

Website

• Product: https://github.com/python-pillow/Pillow/

CPE 2.3info

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CPE 2.2info

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