Privilege Escalation in authentik (CVE-2026-40172)
Summary
Vulnerability in authentik (CVE-2026-40172). Data can be tampered with by attackers. Exploitable via PATCH /api/v3/core/users/{pk}/. Mitigation: upgrade to 2025.12.5, 2026.2.3 or later.
Original description
The description as published by the source.
authentik is an open-source identity provider. In versions prior to 2025.12.5 and 2026.2.0-rc1 through 2026.2.2, the PATCH /api/v3/core/users/{pk}/ API allows a caller with change_user on a target user to assign arbitrary groups through UserSerializer, including groups with is_superuser=True, without requiring enable_group_superuser, leading to privilege escalation. This bypasses the stricter permission model enforced in group-management paths and enables delegated user-management permissions to escalate target users to administrator-equivalent privilege. Users with permissions to update groups or permissions to update users are able to add themselves or other users they have permissions on to users which have superuser permissions. This issue has been fixed in versions 22025.12.5 and 2026.2.3.
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
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-2026-40172 has been found in authentik.
Attackers can target a specific entry point like PATCH /api/v3/core/users/{pk}/ over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 8.1/10.
What to do: upgrade authentik to 2025.12.5, 2026.2.3 or later.
If unsure, ask your IT team or search "authentik CVE-2026-40172" on the vendor's site.
CVE-2026-40172 (authentik) — CWE-269 / CVSS v3 8.1
Attack vector: remote (network-reachable) / no user interaction
Attack surface: PATCH /api/v3/core/users/{pk}/
Patched: 2025.12.5, 2026.2.3 — 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-269) exists in authentik. Attackers reach the vulnerable code path via PATCH /api/v3/core/users/{pk}/.
Check the vendor advisory for the affected versions of authentik. Attack surface: PATCH /api/v3/core/users/{pk}/.
Severity: High (CVSS 8.1/10). Data can be tampered with by attackers.
Update to 2025.12.5, 2026.2.3.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual PATCH /api/v3/core/users/{pk}/ requests with malformed payloads or SQL meta-characters. Run grep -r 'authentik' . 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 'authentik' . | 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
authentikを grep し、稼働しているサービス・バージョンを把握する。 -
2Hunt for indicators of compromise detect
grep 'PATCH /api/v3/core/users/{pk}/' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
PATCH /api/v3/core/users/{pk}/への異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Apply patch patch
Upgrade authentik to 2025.12.5, 2026.2.3ステージング環境で 2025.12.5, 2026.2.3 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 2 で見つけた異常検知の続報チェックを含めること。
-
4Post-deployment verification verify
Replay attack against PATCH /api/v3/core/users/{pk}/ on staging to confirm patch closes the vector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 2 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
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- web github.com
- web github.com