Vulnerability in Werkzeug (CVE-2026-102598)
Summary
Vulnerability in Werkzeug (CVE-2026-102598). Risk of unauthorized operations or information disclosure. Exploitable via safe_join. Mitigation: upgrade to 3.1.9 or later.
Original description
The description as published by the source.
Werkzeug's safe_join function allows Windows device names as filenames when they have an empty ADS marker on NTFS.
This was previously reported as https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact Windows allows special device names with an empty ADS marker, such as NUL:.
send_from_directory uses safe_join to safely serve files at user-specified paths under a directory. If the application is running on Windows and NTFS, and the requested path ends with a special device name, the file will be opened successfully, but reading will hang indefinitely.
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-2026-102598 has been found in Werkzeug.
Attackers can target a specific entry point like safe_join over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Werkzeug to 3.1.9 or later.
If unsure, ask your IT team or search "Werkzeug CVE-2026-102598" on the vendor's site.
CVE-2026-102598 (Werkzeug) — CWE-67
Attack surface: safe_join / send_from_directory
Patched: 3.1.9 — 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-67) exists in Werkzeug. Attackers reach the vulnerable code path via safe_join.
Check the vendor advisory for the affected versions of Werkzeug. Attack surface: safe_join / send_from_directory.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 3.1.9.
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 'Werkzeug' . 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 'Werkzeug' . | 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
Werkzeug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 Werkzeug to 3.1.9ステージング環境で 3.1.9 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 nvd.nist.gov
- advisory github.com
- package github.com
- package pypi.org
- web github.com
- web github.com
- web github.com
- web github.com