CVE-2026-59205

Pillow: Controlled heap out-of-bounds write in `ImageCmsTransform.apply()` via output mode mismatch

Description

Pillow is a Python imaging library. Prior to 12.3.0, Pillow's ImageCms.ImageCmsTransform.apply(im, imOut) API can trigger controlled native heap corruption when the caller supplies an output image whose mode does not match the transform's declared output mode. This issue is fixed in version 12.3.0.

Scores

Weaknesses (CWE)

• CWE-787

Advisories

• GHSA-9hw9-ch79-4vh6 — Pillow: Controlled heap out-of-bounds write in Pillow `ImageCmsTransform.apply()` via output mode mismatch
• PYSEC-2026-3453 — Pillow is a Python imaging library. Prior to 12.3.0, Pillow's ImageCms.ImageCmsTransform.apply(im, imOut) API can trigger controlled native heap corruption when

European references

• ENISA EUVD · EUVD-2026-43746
• GCVE · GCVE-0-2026-59205

CERT-FR advisories

• CERTFR-2026-AVI-1366 — Multiples vulnérabilités dans les produits Splunk · cert.ssi.gouv.fr
• CERTFR-2026-AVI-1094 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr

Affected configurations (NVD CPE)

• cpe:2.3:a:python:pillow:*:*:*:*:*:*:*:* < 12.3.0

Affected products

References

• https://github.com/python-pillow/Pillow/security/advisories/GHSA-9hw9-ch79-4vh6
• https://github.com/python-pillow/Pillow/pull/9715
• https://github.com/python-pillow/Pillow/commit/a9ffc42bedf4fc0a7ef8d6486e7f9e81e3397721
• https://github.com/python-pillow/Pillow/releases/tag/12.3.0

Sources