Authorization Flaw in github.com/mattermost/mattermost-server (CVE-2026-8074)
Summary
Vulnerability in github.com/mattermost/mattermost-server (CVE-2026-8074). Risk of unauthorized operations or information disclosure. Exploitable via PUT /api/v4/users/{id}/active. Mitigation: upgrade to 10.11.18 or later.
Original description
The description as published by the source.
Mattermost versions 11.7.x <= 11.7.0, 10.11.x <= 10.11.17 fail to enforce bot-specific permission checks on the user active status endpoint, which allows a User Manager with user management write access but no Integrations access to deactivate bot accounts via the PUT /api/v4/users/{id}/active API endpoint.. Mattermost Advisory ID: MMSA-2026-00667
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-2026-8074 has been found in github.com/mattermost/mattermost-server.
Attackers can target a specific entry point like PUT /api/v4/users/{id}/active over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 3.8/10.
What to do: upgrade github.com/mattermost/mattermost-server to 10.11.18 or later.
If unsure, ask your IT team or search "github.com/mattermost/mattermost-server CVE-2026-8074" on the vendor's site.
CVE-2026-8074 (github.com/mattermost/mattermost-server) — CWE-863 / CVSS v3 3.8
Attack vector: remote (network-reachable) / no user interaction
Attack surface: PUT /api/v4/users/{id}/active
Patched: 10.11.18 — 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.
Incorrect authorization (CWE-863) exists in github.com/mattermost/mattermost-server. Attackers reach the vulnerable code path via PUT /api/v4/users/{id}/active.
Check the vendor advisory for the affected versions of github.com/mattermost/mattermost-server. Attack surface: PUT /api/v4/users/{id}/active.
Severity: Low (CVSS 3.8/10). Risk of unauthorized operations or information disclosure.
Update to 10.11.18.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual PUT /api/v4/users/{id}/active requests with malformed payloads or SQL meta-characters. Run grep -r 'github.com/mattermost/mattermost-server' . 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 'github.com/mattermost/mattermost-server' . | 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
github.com/mattermost/mattermost-server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 'PUT /api/v4/users/{id}/active' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
PUT /api/v4/users/{id}/active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 github.com/mattermost/mattermost-server to 10.11.18ステージング環境で 10.11.18 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 PUT /api/v4/users/{id}/active 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
- web mattermost.com
- web nvd.nist.gov
- web github.com