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CVE-2026-96643 · GHSA-g4qv-2jxx-769h

Pillow: PNG eXIf chunk makes EXIF parsing run in quadratic time

Risk score
58/100
CVSS
7.1 v4.0
Exploit chance (30 days)
0.3%
Published
21 Oct 2026

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What to know

What it is
Pillow is a Python imaging library. From 11.0.0 until 13.0.0, Exif.load() in src/PIL/Image.py repeatedly slices the remaining EXIF data while it begins with the six-byte Exif header. src/PIL/PngImagePlugin.py accepts an uncapped PNG eXIf chunk, so a file filled with repeated headers causes a new shrinking copy on ever…
Affected
Pillow (pip) >= 11.0.0, < 13.0.0
Fix
Upgrade Pillow to 13.0.0 or later.
Exploitation
No known exploitation

Story map

Story map: PillowTHE FLAWSTHE FIXCVE-2026-96643PNG eXIf chunk makes EXIFparsing run in quadratic timeCVSS 7.1 · 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 weaknessDenial of service (CWE-407)70 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-2026-96643: PNG eXIf chunk makes EXIF parsing run in quadratic time (CVSS 7.1 · 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 7.1 high
  • Remotely exploitable without logging in
  • On your watchlist: PyPI

Affected packages

PackageEcosystemVulnerableFixed in
Pillowpip>= 11.0.0, < 13.0.013.0.0

References

Original description

Pillow is a Python imaging library. From 11.0.0 until 13.0.0, Exif.load() in src/PIL/Image.py repeatedly slices the remaining EXIF data while it begins with the six-byte Exif header. src/PIL/PngImagePlugin.py accepts an uncapped PNG eXIf chunk, so a file filled with repeated headers causes a new shrinking copy on every iteration and quadratic CPU work. The condition is reachable through Image.getexif(), Image._getexif(), and ImageOps.exif_transpose(), including common photo-upload rotation workflows. This issue is fixed in version 13.0.0.

Last activity 21 Oct 2026. Patch Forecast updates every hour.