How severe is GHSA-vjc4-5qp5-m44j?

No CVSS score has been assigned to GHSA-vjc4-5qp5-m44j yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-vjc4-5qp5-m44j?

GHSA-vjc4-5qp5-m44j affects the following packages: pillow (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-vjc4-5qp5-m44j?

Update pillow to 12.3.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vjc4-5qp5-m44j is resolved across your whole dependency graph.

How do I detect GHSA-vjc4-5qp5-m44j in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pillow. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-vjc4-5qp5-m44j if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-vjc4-5qp5-m44j?

O3 pinpoints whether GHSA-vjc4-5qp5-m44j is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-vjc4-5qp5-m44j actively exploited in the wild?

No public exploit code has been indexed for GHSA-vjc4-5qp5-m44j yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What type of vulnerability is GHSA-vjc4-5qp5-m44j?

GHSA-vjc4-5qp5-m44j is classified as CWE-789 (CWE-789), CWE-770 (CWE-770). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-vjc4-5qp5-m44j published, and has it been updated?

GHSA-vjc4-5qp5-m44j was published on July 20, 2026 and was last updated on July 23, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

Not in CISA KEV

GHSA-vjc4-5qp5-m44j

Fix: python-pillow/Pillow#9704

GHSA-vjc4-5qp5-m44j is a CWE-789 vulnerability in pillow. O3 Security confirms whether GHSA-vjc4-5qp5-m44j is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

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

Also known asBIT-pillow-2026-59204CVE-2026-59204PYSEC-2026-3496

Published

Jul 20, 2026

Updated

Jul 23, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Jul 23, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

🐍pillow

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

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:

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:

python exercise_j2k_tile_realloc.py load poc_3664_rgba_tile1832.jp2

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

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 Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`pillow`	≥ 8.2.0&&< 12.3.0	12.3.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pillow. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update pillow to 12.3.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vjc4-5qp5-m44j is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-vjc4-5qp5-m44j is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-vjc4-5qp5-m44j. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### 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

O3 Security · Impact-Aware SCA

Is GHSA-vjc4-5qp5-m44j in your dependencies?

O3 detects GHSA-vjc4-5qp5-m44j across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works