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CVE-2026-112396 · GHSA-4rr5-89j8-mwwm

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

Risk score
48/100
CVSS
5.9 v3.1
Exploit chance (30 days)
0.5%
Published
19 Oct 2026

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What to know

What it is
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…
Affected
pillow (pip) >= 11.3.0, < 13.0.0
Fix
Upgrade pillow to 13.0.0 or later.
Exploitation
No known exploitation

Story map

Story map: PillowTHE FLAWSTHE FIXCVE-2026-112396Pillow: Heap use-after-freewhen encoding TIFF to anin-memory bufferCVSS 5.9 · EPSS 0%CVE-2026-112393Heap buffer overflow in_tiffWriteProc when savingTIFF to BytesIOCVSS 9.2 · EPSS 1%CVE-2026-96639Pillow multi-frame loaders canreuse stale native imagestorage after mode transitionsCVSS 9.8 · EPSS 1%CVE-2026-112900Argument Injection inGhostscript call, potentiallyleading into RCECVSS 9.2 · EPSS 0%Upgrade Pillow13.0.0or later on your release lineWho is exposed{'products': ['Pillow'],'packages': ['Pillow'], 'versions':['>= 2.0.0, < 13.0.0']}AMBER · PATCH THIS WEEKPillowPillow has a heap bufferoverflow and stale-heapdisclosure in _tiffWriteProcwhen saving compressed TIFFdata through libtiff to a targetwithout a usable fileno(). Thiscan crash the process and may…Where it standsPublic proof of concept1 outlet covering itHOW IT UNFOLDEDOfficial record on the left, the press on the right, oldest first.23 Oct · The Hacker NewsCritical Flaw in Python’s Popular Pillow ImageLibrary Allows Code Execution via a Crafted ImageCONNECTS TOSame weaknessUse-after-free (CWE-416)400 other warnings in 30 days →
Story map: the flaws, the fix, how it unfolded and what it connects to. Boxes link to the record or article.

At a glance

Pillow: Amber, patch this week. Pillow has a heap buffer overflow and stale-heap disclosure in _tiffWriteProc when saving compressed TIFF data through libtiff to a target without a usable fileno(). This can crash the process and may allow code execution.

The flaws

  • CVE-2026-112396: Pillow: Heap use-after-free when encoding TIFF to an in-memory buffer (CVSS 5.9 · EPSS 0%)
  • CVE-2026-112393: Heap buffer overflow in _tiffWriteProc when saving TIFF to BytesIO (CVSS 9.2 · EPSS 1%)
  • CVE-2026-96639: Pillow multi-frame loaders can reuse stale native image storage after mode transitions (CVSS 9.8 · EPSS 1%)
  • CVE-2026-112900: Argument Injection in Ghostscript call, potentially leading into RCE (CVSS 9.2 · EPSS 0%)

The fix

Upgrade Pillow: 13.0.0 or later on your release line

Who is exposed: {'products': ['Pillow'], 'packages': ['Pillow'], 'versions': ['>= 2.0.0, < 13.0.0']}

Where it stands

  • Public proof of concept
  • 1 outlet covering it

How it unfolded

  1. 23 Oct, The Hacker News (press): Critical Flaw in Python’s Popular Pillow Image Library Allows Code Execution via a Crafted Image

Connects to

Why it is Yellow

  • CVSS 5.9 medium
  • On your watchlist: PyPI

Affected packages

PackageEcosystemVulnerableFixed in
pillowpip>= 11.3.0, < 13.0.013.0.0

References

Original 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.

Last activity 19 Oct 2026. Patch Forecast updates every hour.