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High

Pillow JPEG2000 tiled decode retains a growing scratch buffer and can be used for denial of service

  • Disclosed: 20.07.2026
  • Updated: 11.10.2026 15:17

Summary

src/libImaging/Jpeg2KDecode.c:853 accumulates total_component_width across every tile in a JPEG2000 image instead of recomputing it per tile. That accumulated value is then used in the tile_bytes calculation at src/libImaging/Jpeg2KDecode.c:868, which can make the decoder grow state->buffer via realloc at src/libImaging/Jpeg2KDecode.c:876 up to roughly one full image's decompressed size even when each tile is small. A crafted tiled JPEG2000 file can therefore force substantially higher transient memory usage and trigger out-of-memory failures during decoding. Based on current evidence, the supported impact is denial of service, not memory corruption.

Details

  • Location: src/libImaging/Jpeg2KDecode.c:853
  • Root cause: total_component_width is initialized only once before the tile loop and keeps growing across tiles. It is then used to derive tile_bytes, so later tiles are treated as if they had the combined component width of all earlier tiles.
  • Dangerous operation: tile_bytes is promoted into tile_info.data_size, then state->buffer is grown with realloc at src/libImaging/Jpeg2KDecode.c:876.
  • Reachability: any attacker-controlled JPEG2000 image with many tiles reaches this path during normal Image.open(...).load() decoding.

PoC

The attached helper script and testcase were used: exercise_j2k_tile_realloc.zip

Generate the testcase:

bash
pythonexercise_j2k_tile_realloc.py make poc_3664_rgba_tile1832.jp2 \
  --size 3664 --tile 1832

Expected geometry from the helper:

  • image size: 3664 x 3664
  • mode: RGBA
  • tile size: 1832 x 1832 (2x2 tiles)
  • image_bytes=53699584
  • uncapped RSS observed:
    • vulnerable build: maxrss_kb=180264
    • fixed comparison build: maxrss_kb=138404

Load it with the current vulnerable build:

bash
python exercise_j2k_tile_realloc.py load poc_3664_rgba_tile1832.jp2

Load it again under a 160 MB address-space cap:

bash
python exercise_j2k_tile_realloc.py load poc_3664_rgba_tile1832.jp2 --limit-mb 160

Impact

Conservative impact: denial of service through memory exhaustion during JPEG2000 decoding.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Python (PyPI) pillow >= 8.2.0, < 12.3.0 12.3.0

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-770, CWE-789
Platform
Python (PyPI)
Package
pillow
Disclosed
20.07.2026
Updated
11.10.2026 15:17

Sources and licenses

OSV / GitHub Advisory Database - PYSEC-2026-3496 - PyPA Advisory Database; CC BY 4.0

OSV / GitHub Advisory Database - GHSA-vjc4-5qp5-m44j - 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 (81) in the archive
Total entries
81
First → latest
04.2014 10.2026
Without a fix
0
Exploited in attacks
1

Severity breakdown

  • Critical 10
  • High 53
  • Medium 16
  • Low 1
  • Unrated 1

Disclosures per year

earlier: 12

Severity:
  1. Pillow: Out-of-bounds access in _imagingmorph on a zero-width image
    High CVE-2026-112397 < 13.0.0 13.0.0
  2. Pillow: GIF seek keeps rejected size after DecompressionBombError, allowing DoS
    High CVE-2026-112400 >= 9.2.0, < 13.0.0 13.0.0
  3. 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
  4. Pillow JPEG2000 tiled decode retains a growing scratch buffer and can be used for denial of service this entry
    High CVE-2026-59204 >= 8.2.0, < 12.3.0 12.3.0
  5. Pillow: Decompression Bomb DoS via PdfParser.PdfStream.decode()
    High · 7.5 CVE-2026-59200 >= 5.1.0, < 12.3.0 12.3.0
  6. 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
  7. 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
  8. 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
  9. 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
  10. Pillow: `FontFile.compile()`: `Image.new()` called without `_decompression_bomb_check()`
    High · 7.5 CVE-2026-54060 < 12.3.0 12.3.0
  11. 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
  12. 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
  13. Pillow `GdImageFile._open()`: image dimensions accepted without `_decompression_bomb_check()`
    High · 7.5 CVE-2026-55380 < 12.3.0 12.3.0
  14. Pillow has an OOB Write with Invalid PSD Tile Extents (Integer Overflow)
    High CVE-2026-42311 >= 10.3.0, < 12.2.0 12.2.0
  15. FITS GZIP decompression bomb in Pillow
    High · 7.5 CVE-2026-40192 >= 10.3.0, < 12.2.0 12.2.0
  16. Pillow affected by out-of-bounds write when loading PSD images
    High CVE-2026-25990 >= 10.3.0, < 12.1.1 12.1.1
  17. Pillow vulnerability can cause write buffer overflow on BCn encoding
    High · 7.1 CVE-2025-48379 >= 11.2.0, < 11.3.0 11.3.0
  18. Pillow buffer overflow vulnerability
    High · 6.7 CVE-2024-28219 < 10.3.0 10.3.0
  19. Arbitrary Code Execution in Pillow
    Critical · 8.1 CVE-2023-50447 < 10.2.0 10.2.0
  20. An issue was discovered in Pillow before 10.0.0. It is a Denial of Service that uncontrollably allocates memory to process a given task, potentially causing a service to crash by having it run out of
    High · 7.5 CVE-2023-44271 < 10.0.0 10.0.0
  21. libwebp: OOB write in BuildHuffmanTable
    High · 8.8 Exploited in attacks CVE-2023-4863 < 10.0.1 10.0.1
  22. Pillow before 9.3.0 allows denial of service via SAMPLESPERPIXEL.
    High · 7.5 CVE-2022-45199 >= 9.2.0, < 9.3.0 9.3.0
  23. Pillow before 9.2.0 performs Improper Handling of Highly Compressed GIF Data (Data Amplification).
    High · 7.5 CVE-2022-45198 < 9.2.0 9.2.0
  24. Buffer over-flow in Pillow
    High · 7.5 CVE-2022-30595 >= 9.1.0, < 9.1.1 9.1.1
  25. Path traversal in Pillow
    High · 9.1 CVE-2022-24303 < 9.0.1 9.0.1
  26. Arbitrary expression injection in Pillow
    Critical · 9.8 CVE-2022-22817 < 9.0.1 9.0.1
  27. Uncontrolled Resource Consumption in pillow
    High · 7.5 CVE-2021-23437 >= 5.2.0, < 8.3.2 8.3.2
  28. Buffer Overflow in Pillow
    Critical · 9.8 CVE-2021-34552 < 8.3.0 8.3.0
  29. Uncontrolled Resource Consumption in Pillow
    High · 7.5 CVE-2021-28677 < 8.2.0 8.2.0
  30. Potential infinite loop in Pillow
    High · 7.5 CVE-2021-28676 < 8.2.0 8.2.0
  31. Pillow Out-of-bounds Read vulnerability
    High · 9.1 CVE-2021-25288 >= 2.4.0, < 8.2.0 8.2.0
  32. Out-of-bounds Read in Pillow
    High · 9.1 CVE-2021-25287 >= 2.4.0, < 8.2.0 8.2.0
  33. Pillow denial of service
    High · 5.5 CVE-2021-28675 < 8.2.0 8.2.0
  34. Out of bounds read in Pillow
    High · 7.5 CVE-2021-25293 >= 4.3.0, < 8.1.1 8.1.1
  35. Out of bounds read in Pillow
    High · 7.5 CVE-2021-25291 < 8.2.0 8.2.0
  36. Out-of-bounds Write in Pillow
    High · 7.5 CVE-2021-25290 < 8.1.1 8.1.1
  37. Out of bounds write in Pillow
    Critical · 9.8 CVE-2021-25289 < 8.1.1 8.1.1
  38. Pillow Denial of Service by Uncontrolled Resource Consumption
    High · 7.5 CVE-2021-27923 < 8.1.2 8.1.2
  39. Pillow Uncontrolled Resource Consumption
    High · 7.5 CVE-2021-27922 < 8.1.2 8.1.2
  40. Pillow Denial of Service by Uncontrolled Resource Consumption
    High · 7.5 CVE-2021-27921 < 8.1.2 8.1.2
Show more (20) Showing 40 of 63

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