Vulnerability in psd-tools (CVE-2026-59991)
Summary
Vulnerability in psd-tools (CVE-2026-59991). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 1.17.4 or later.
Original description
The description as published by the source.
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 unrecoverable OOM-kill.
Steps to reproduce
# pip install psd-tools==1.17.2
from psd_tools import PSDImage
psd = PSDImage.open("psd-psdtools-grammar-d23.psd")
psd.composite() # commits ~3 GB from a 49-byte file and returns (warning only)
PoC (49 bytes), reconstruct with:
base64 -d > psd-psdtools-grammar-d23.psd <<'EOF'
OEJQUwABAAAAAAAAAAYAACg4AAAXTAAIAAMAAAAAAAAAAAAAAAAAAUNIUIFU+yQtDw==
EOF
Verify:
7d8ebf03a54393cb0359ecf4b676d1b08c9a8c6afdd0…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-59991 has been found in psd-tools.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade psd-tools to 1.17.4 or later.
If unsure, ask your IT team or search "psd-tools CVE-2026-59991" on the vendor's site.
CVE-2026-59991 (psd-tools) — CWE-789 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 1.17.4 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-789) exists in psd-tools.
Check the vendor advisory for the affected versions of psd-tools.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 1.17.4.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'psd-tools' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'psd-tools' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
psd-toolsを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade psd-tools to 1.17.4ステージング環境で 1.17.4 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-59991 psd-tools
- Ubuntu UBUNTU-CVE-2026-59991 psd-tools
References
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- package pypi.org
- web github.com
- web github.com
- web github.com