What’s Vulnerable › Vulnerabilities

CVE-2026-112396: Pillow: Heap use-after-free when encoding TIFF to an in-memory buffer

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-10-19 · updated 2026-10-26
• Weakness: CWE-416

Description

Pillow is a Python imaging library. From 11.3.0 until 13.0.0, Pillow has a heap use-after-free when libtiff rejects a tag while encoding TIFF data to an in-memory buffer. When an application saves attacker-influenced TIFF tags to BytesIO, libtiff can reject a tag during encoding in ImagingLibTiffEncode; the error path then frees the output buffer without closing or clearing the TIFF handle, and later cleanup flushes through the write callback into freed memory, which can crash the process and may enable code execution. This issue is fixed in version 13.0.0.

Affected products

• python-pillow Pillow: from 11.3.0 before 13.0.0 — fixed in 13.0.0
• python-pillow Pillow: from 11.3.0, < 13.0.0

How to fix

Upgrade to a fixed version: python-pillow Pillow 13.0.0. Check the vendor advisory for mitigations.

References

• https://github.com/python-pillow/Pillow/commit/dc95da20207827a062cfbf551ee9f6031465a8bb
• https://github.com/python-pillow/Pillow/releases/tag/13.0.0
• https://github.com/python-pillow/Pillow/security/advisories/GHSA-4rr5-89j8-mwwm

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