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PatchSiren cyber security CVE debrief

CVE-2026-42311 python-pillow CVE debrief

CVE-2026-42311 affects Pillow, a Python imaging library, when it processes malicious PSD files. According to the advisory and NVD record, versions 10.3.0 through before 12.2.0 are vulnerable to memory corruption, which can result in a crash or arbitrary code execution. The issue is patched in Pillow 12.2.0.

Vendor
python-pillow
Product
Pillow
CVSS
HIGH 8.6
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-09
Original CVE updated
2026-07-24
Advisory published
2026-05-09
Advisory updated
2026-07-24

Who should care

Teams that use Pillow to load, transform, validate, or thumbnail untrusted image files—especially PSD content—should treat this as high priority. This includes application developers, platform teams, CI/image-processing pipelines, and security teams that ingest user-supplied media.

Technical summary

The vulnerability is a memory-corruption flaw triggered during PSD file processing in Pillow versions 10.3.0 to before 12.2.0. The supplied GitHub advisory metadata maps the issue to CWE-190 and CWE-787, and NVD rates it HIGH with a CVSS 4.0 score of 8.6. The official fix is available in Pillow 12.2.0.

Defensive priority

High. Memory corruption in an image parser can expose systems that handle untrusted files to crashes and, in the worst case, arbitrary code execution.

Recommended defensive actions

  • Upgrade Pillow to version 12.2.0 or later wherever it is used.
  • Inventory services, jobs, and libraries that accept or process PSD files through Pillow.
  • Treat untrusted PSD uploads as high risk until patched; consider temporary input restrictions or validation controls.
  • Rebuild and redeploy any containers, wheels, or lockfiles that pin a vulnerable Pillow release.
  • Add regression tests that cover PSD handling paths after the upgrade.
  • Monitor downstream dependencies that vendor or bundle Pillow to ensure they also receive the fix.

Evidence notes

The CVE description states that Pillow versions from 10.3.0 to before 12.2.0 can suffer memory corruption when processing a malicious PSD file, with potential crash or arbitrary code execution, and that 12.2.0 contains the patch. NVD provides a HIGH 8.6 CVSS 4.0 score and references the GitHub commit, pull request, release tag, and security advisory.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-42311 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-42311

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-42311 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-42311

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.