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High

Pillow: MSP RLE decoder expands a tiny file into unbounded memory

  • Disclosed: 21.10.2026
  • Updated: 23.10.2026 00:10

Summary

The MSP RLE decoder in Pillow expands run-length data into an in-memory buffer with no cap tied to the declared image size. A small file that passes the pixel-count check can force hundreds of megabytes or more of allocation when the application loads pixels.

Details

The MSP decoder writes each run into an unbounded io.BytesIO and can expand roughly 85x per run:

  • src/PIL/MspImagePlugin.py:144-146

Impact

This issue leads to a memory-exhaustion denial of service from a tiny crafted image in any application that loads pixels. Because the expansion is decoupled from the declared pixel count, MAX_IMAGE_PIXELS does not bound it.

What to do

Upgrade Pillow to version 13.0.0 or later.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Python (PyPI) pillow >= 4.1.0, < 13.0.0 13.0.0

References

CVSS score -
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness (CWE)
CWE-409
Platform
Python (PyPI)
Package
pillow
Disclosed
21.10.2026
Updated
23.10.2026 00:10

Sources and licenses · Edited or translated by DockRay; source rights and applicable licenses are retained.

OSV / GitHub Advisory Database - GHSA-gg2r-wvfm-q9rx - CC BY 4.0

Vulnerability history: pillow

All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (100) in the archive
Total entries
100
First → latest
04.2014 10.2026
Without a fix
0
Exploited in attacks
1

Severity breakdown

  • Critical 13
  • High 58
  • Medium 27
  • Low 1
  • Unrated 1

Disclosures per year

earlier: 12

Severity:
  1. Pillow multi-frame loaders can reuse stale native image storage after mode transitions
    Critical · 9.8 CVE-2026-96639 >= 11.0.0, < 13.0.0 13.0.0
  2. Pillow: MSP RLE decoder expands a tiny file into unbounded memory this entry
    High CVE-2026-112892 >= 4.1.0, < 13.0.0 13.0.0
  3. Pillow: Infinite loop in MIC n_frames when the embedded TIFF
    High CVE-2026-112390 >= 7.2.0, < 13.0.0 13.0.0
  4. Pillow: NULL dereference in ImagingExpand via rank filters on zero-size images
    High CVE-2026-112392 < 13.0.0 13.0.0
  5. Pillow: NULL pointer dereference in Image.merge via an unvalidated band 0
    High CVE-2026-112405 >= 12.0.0, < 13.0.0 13.0.0
  6. Pillow: Invalid free in FreeType glyph rendering when a stroker is active
    High CVE-2026-112893 >= 10.0.0, < 13.0.0 13.0.0
  7. Pillow: Argument Injection in Ghostscript call, potentially leading into RCE
    Critical CVE-2026-112900 >= 2.6.0, < 13.0.0 13.0.0
  8. Pillow: Out-of-bounds access in _imagingmorph on a zero-width image
    High CVE-2026-112397 < 13.0.0 13.0.0
  9. Pillow: GIF seek keeps rejected size after DecompressionBombError, allowing DoS
    High CVE-2026-112400 >= 9.2.0, < 13.0.0 13.0.0
  10. Pillow: Unbounded recursion parsing a PDF page tree or trailer chain (incomplete fix for CVE-2026-42310)
    High CVE-2026-112895 >= 5.1.0, < 13.0.0 13.0.0
  11. Pillow: Heap buffer overflow in ImagingJpegDecode
    Critical CVE-2026-112403 < 13.0.0 13.0.0
  12. Pillow JPEG2000 tiled decode retains a growing scratch buffer and can be used for denial of service
    High CVE-2026-59204 >= 8.2.0, < 12.3.0 12.3.0
  13. Pillow: Decompression Bomb DoS via PdfParser.PdfStream.decode()
    High · 7.5 CVE-2026-59200 >= 5.1.0, < 12.3.0 12.3.0
  14. Pillow: Out-of-bounds read via attacker-controlled row stride on Pillow's mmap path (McIdas AREA files)
    High CVE-2026-54058 < 12.3.0 12.3.0
  15. Pillow: Heap out-of-bounds write in `ImageFilter.RankFilter` via integer overflow in `ImagingExpand`
    High · 8.2 CVE-2026-59197 < 12.3.0 12.3.0
  16. Pillow: Controlled heap out-of-bounds write in Pillow `ImageCmsTransform.apply()` via output mode mismatch
    High · 7.5 CVE-2026-59205 < 12.3.0 12.3.0
  17. Pillow: Heap out-of-bounds write `Image.paste()` / `Image.crop()` via signed coordinate overflow
    High · 7.5 CVE-2026-59199 < 12.3.0 12.3.0
  18. Pillow: `FontFile.compile()`: `Image.new()` called without `_decompression_bomb_check()`
    High · 7.5 CVE-2026-54060 < 12.3.0 12.3.0
  19. Pillow `PcfFontFile._load_bitmaps()`: `Image.frombytes()` called without `_decompression_bomb_check()` — bomb protection bypass via PCF font loading
    High · 7.5 CVE-2026-54059 < 12.3.0 12.3.0
  20. Pillow `BdfFontFile`: `Image.new()` called without `_decompression_bomb_check()` — bomb protection bypass via font loading
    High · 7.5 CVE-2026-55379 < 12.3.0 12.3.0
Show more (20) Showing 20 of 71

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