Vulnerability in Pillow (CVE-2026-59200)
Summary
Vulnerability in Pillow (CVE-2026-59200). Risk of unauthorized operations or information disclosure. Exploitable via PdfParser.py. Mitigation: upgrade to 12.3.0 or later.
Original description
The description as published by the source.
Pillow is a Python imaging library. From 5.1.0 until 12.3.0, PdfParser.PdfStream.decode() in PIL/PdfParser.py calls zlib.decompress() with bufsize set to the PDF stream Length field without bounding the decompressed output size, allowing a crafted FlateDecode PDF stream to exhaust memory from a small file. This issue is fixed in version 12.3.0.
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-2026-59200 has been found in Pillow.
Attackers can target a specific entry point like PdfParser.py over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade Pillow to 12.3.0 or later.
If unsure, ask your IT team or search "Pillow CVE-2026-59200" on the vendor's site.
CVE-2026-59200 (Pillow) — CWE-400 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: PdfParser.py / bufsize / Length / PdfParser
Patched: 12.3.0 — 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-400) exists in Pillow. Attackers reach the vulnerable code path via PdfParser.py without authentication.
Check the vendor advisory for the affected versions of Pillow. Attack surface: PdfParser.py / bufsize / Length / PdfParser.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 12.3.0.
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 'Pillow' . 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 'Pillow' . | 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
Pillow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 Pillow to 12.3.0ステージング環境で 12.3.0 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-2026-59200 pillow
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- advisory github.com
- package github.com
- package pypi.org
- patch github.com
- patch github.com
- web github.com