Pillow TGA RLE encoder can serialize up to ~57 KB of adjacent heap data into generated images

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:L

EPSS

• CVE-2026-59198: 0.31% estimated exploitation activity in the next 30 days; percentile 24.25 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Pillow's TGA RLE encoder reads past its row buffer when saving a mode "1" image. Adjacent process heap bytes can be copied into the generated TGA file. The bug is reachable through the public save API: Older affected Pillow versions use the equivalent public option rle=True. For mode "1", Pillow allocates a packed row buffer of ceil(width / 8) bytes, but ImagingTgaRleEncode() treats the row as one full byte per pixel. The maximum valid TGA width is 65535. At that width: On non-ASAN Pillow 12.2.0, the public-only maximum-width PoC below serialized 57297 bytes from distinct out-of-bounds source offsets into one returned TGA, covering 99.92% of the maximum adjacent heap window. No heap grooming, ctypes, private API, or malformed input file was used. The disclosure is emitted across many TGA packet payload copies of at most 128 bytes each, not one large memcpy(). Details src/PIL/TgaImagePlugin.py allows mode "1" TGA output and selects the tgarle encoder when RLE compression is…

Published by the source

20 Jul 2026, 23:09 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 13:49 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-fj7v-r99m-22gq

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-fj7v-r99m-22gq

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# Patch Next advisory brief: CVE-2026-59198

Advisory: Pillow TGA RLE encoder can serialize up to ~57 KB of adjacent heap data into generated images
IDs: CVE-2026-59198, GHSA-fj7v-r99m-22gq
Record: https://patchnext.com/advisories/cve-2026-59198 (revision 2, source checked 26 Oct 2026, 13:49 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pillow 12.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI pillow: affected >= 5.2.0, < 12.3.0; fixed in 12.3.0

## Suggested inspection (read-only)
- `python -m pip show pillow`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on pillow.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-fj7v-r99m-22gq (OSV record GHSA-fj7v-r99m-22gq lists affected ranges: PyPI pillow >=5.2.0 <12.3.0 (fixed))
- Verified: https://github.com/advisories/GHSA-fj7v-r99m-22gq (GitHub-reviewed advisory GHSA-fj7v-r99m-22gq lists affected ranges: PyPI pillow >=5.2.0 <12.3.0)

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