psd-tools composite/numpy has uncontrolled memory allocation via crafted PSD geometry

Exploitation

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

CVSS

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

EPSS

• CVE-2026-59991: 0.52% estimated exploitation activity in the next 30 days; percentile 44.07 (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 PSDImage.composite() (and .numpy()) allocate the output image buffer from the PSD's header geometry (width × height × channels × depth, and per-layer rectangles) before validating those values against the actual file contents. A tiny crafted PSD declaring huge dimensions causes a multi-gigabyte allocation. Critically, composite() then returns a (black) image with only a warning, no exception is raised, so a caller cannot detect or guard against it. Impact On psd-tools 1.17.2 (latest), default usage, a 49-byte PSD makes composite() commit ~3 GB and return successfully (warning only); .numpy() reaches ~7.5 GB, and the per-layer rectangle is a second lever (up to ~32 GB), all from an input under 100 bytes (input-to-commit amplification over 1000×). Because the buffer is committed before validation and no exception is thrown, any service that composites untrusted PSDs is exposed to denial of service: on a host with less RAM than the attacker-declared geometry the allocation is an…

Published by the source

22 Sep 2026, 19:45 UTC

Last modified by the source

1 Oct 2026, 17:56 UTC

Source last checked

26 Oct 2026, 13:54 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-8q6g-vjhf-jp8m

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-8q6g-vjhf-jp8m

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-8q6g-vjhf-jp8m

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# Patch Next advisory brief: CVE-2026-59991

Advisory: psd-tools composite/numpy has uncontrolled memory allocation via crafted PSD geometry
IDs: CVE-2026-59991, GHSA-8q6g-vjhf-jp8m
Record: https://patchnext.com/advisories/cve-2026-59991 (revision 3, source checked 26 Oct 2026, 13:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: psd-tools 1.17.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI psd-tools: affected < 1.17.4; fixed in 1.17.4

## Suggested inspection (read-only)
- `python -m pip show psd-tools`: 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 psd-tools.
- 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://github.com/advisories/GHSA-8q6g-vjhf-jp8m (GitHub-reviewed advisory GHSA-8q6g-vjhf-jp8m lists affected ranges: PyPI psd-tools >=0 <1.17.4)
- Verified: https://osv.dev/vulnerability/GHSA-8q6g-vjhf-jp8m (OSV record GHSA-8q6g-vjhf-jp8m lists affected ranges: PyPI psd-tools >=0 <1.17.4 (fixed))

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