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.
Original description
The description as published by the source.
Pillow is a Python imaging library. Prior to 12.3.0, WindowsViewer.get_command() constructed a cmd.exe shell command by directly embedding a file path into an f-string without escaping and passed the result to subprocess.Popen(..., shell=True), allowing shell metacharacters in the file path to inject arbitrary cmd.exe commands. 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-2026-55798 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.
OS command injection (CWE-78) exists in Pillow. Attackers reach the vulnerable code path via cmd.exe without authentication.
Check the vendor advisory for the affected versions of Pillow. Attack surface: cmd.exe / MacViewer / UnixViewer / shlex.quote.
Severity: Medium (CVSS 4.5/10). 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
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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。 -
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
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- patch github.com
- patch github.com
- patch github.com
- web github.com
- web github.com
- web github.com