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CVE-2026-55798
medium
CVSS 4.5
OS Command Injection in Pillow (CVE-2026-55798)
Summary
OS command injection in Pillow (CVE-2026-55798). Risk of unauthorized operations or information disclosure. Exploitable via ``cmd.exe``. Mitigation: upgrade to `12.3.0` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-55798** has been found in Pillow.
Attackers can target a specific entry point like ``cmd.exe`` over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.5/10.
What to do: upgrade Pillow to **12.3.0** or later.
If unsure, ask your IT team or search "Pillow CVE-2026-55798" on the vendor's site.
CVE-2026-55798 (Pillow) — CWE-78 / CVSS v3 4.5
Attack vector: local / unauthenticated
Attack surface: `cmd.exe` / `MacViewer` / `UnixViewer` / `shlex.quote`
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.
❓ What is the problem
**OS command injection** (CWE-78) exists in Pillow. Attackers reach the vulnerable code path via ``cmd.exe`` without authentication.
📍 Affected scope
Pillow — . Attack surface: `cmd.exe` / `MacViewer` / `UnixViewer` / `shlex.quote`.
🔥 Severity
Severity: Medium (CVSS 4.5/10). Risk of unauthorized operations or information disclosure
🔧 How to fix
Update to **12.3.0**.
🛡️ Workaround
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
🔍 Detection
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 (7 steps)
Concrete steps and command examples for SOC/SRE teams to execute in order
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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。
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6Apply 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と、Step 3 で見つけた異常検知の続報チェックを含めること。
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7Post-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 Step 3 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
pip
Pillow
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"12.3.0"}]}]
References
- web https://github.com/python-pillow/Pillow/blob/main/docs/releasenotes/12.3.0.rst
- web https://github.com/python-pillow/Pillow/commit/8404ea5fe5df40fc34aa1e51403dd6fce0778b8a
- web https://github.com/python-pillow/Pillow/commit/88194166691b7b603529b8b036ab3ab9cedd2de4
- web https://github.com/python-pillow/Pillow/commit/b0e06caa64c1405aa3da0bb1d2bd9a77ca22de7f
- web https://github.com/python-pillow/Pillow/security/advisories/GHSA-4x4j-2g7c-83w6
- web https://nvd.nist.gov/vuln/detail/CVE-2026-55798
- web https://github.com/pypa/advisory-database/tree/main/vulns/pillow/PYSEC-2026-2257.yaml
- web https://github.com/advisories/GHSA-4x4j-2g7c-83w6