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CVE-2026-114501 · GHSA-654x-cwwv-5j9c

Pillow: Arrow export leaks stale heap memory when PILLOW_ALIGNMENT > 1

Risk score
49/100
CVSS
6.3 v4.0
Exploit chance (30 days)
0.4%
Published
21 Oct 2026

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What to know

What it is
Pillow is a Python imaging library. From 11.2.1 until 13.0.0, Arrow export assumes that an image's rows are tightly contiguous and exports from im->blocks[0].ptr even when PILLOW_ALIGNMENT makes aligned_linesize include row padding or an aligned offset before the first row. The resulting Arrow buffer can include unini…
Affected
Pillow (pip) >= 11.2.1, < 13.0.0
Fix
Upgrade Pillow to 13.0.0 or later.
Exploitation
No known exploitation

Story map

Story map: PillowTHE FLAWSTHE FIXCVE-2026-114501Arrow export leaks stale heapmemory whenPILLOW_ALIGNMENT > 1CVSS 6.3 · 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 weaknessCWE-226 (CWE-226)3 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-2026-114501: Arrow export leaks stale heap memory when PILLOW_ALIGNMENT > 1 (CVSS 6.3 · 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 6.3 medium
  • On your watchlist: PyPI

Affected packages

PackageEcosystemVulnerableFixed in
Pillowpip>= 11.2.1, < 13.0.013.0.0

References

Original description

Pillow is a Python imaging library. From 11.2.1 until 13.0.0, Arrow export assumes that an image's rows are tightly contiguous and exports from im->blocks[0].ptr even when PILLOW_ALIGNMENT makes aligned_linesize include row padding or an aligned offset before the first row. The resulting Arrow buffer can include uninitialized padding, bytes preceding the first row, or stale heap contents from previously freed images. Applications that configure alignment and export images to Arrow can therefore disclose one user's pixels or other process memory to another user. This issue is fixed in version 13.0.0.

Last activity 23 Oct 2026. Patch Forecast updates every hour.