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CVE-2026-7387
high
CVSS 8.8
Authorization Flaw in github.com/mattermost/mattermost-server (CVE-2026-7387)
Summary
vulnerability in github.com/mattermost/mattermost-server (CVE-2026-7387). Successful exploitation can lead to full system takeover. Mitigation: upgrade to `10.11.17` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-7387** has been found in github.com/mattermost/mattermost-server.
Successful exploitation can lead to full system takeover. CVSS score: 8.8/10.
What to do: upgrade github.com/mattermost/mattermost-server to **10.11.17** or later.
If unsure, ask your IT team or search "github.com/mattermost/mattermost-server CVE-2026-7387" on the vendor's site.
CVE-2026-7387 (github.com/mattermost/mattermost-server) — CWE-863 / CVSS v3 8.8
Attack vector: remote (network-reachable) / no user interaction
Patched: `10.11.17` — 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
**incorrect authorization** (CWE-863) exists in github.com/mattermost/mattermost-server.
📍 Affected scope
github.com/mattermost/mattermost-server — .
🔥 Severity
Severity: High (CVSS 8.8/10). Successful exploitation can lead to full system takeover
🔧 How to fix
Update to **10.11.17**.
🛡️ 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 'github.com/mattermost/mattermost-server' .` 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
-
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。
-
6Apply patch patch
Upgrade github.com/mattermost/mattermost-server to 10.11.17ステージング環境で 10.11.17 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。
-
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
go
github.com/mattermost/mattermost-server
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"10.11.17"}]}]
go
github.com/mattermost/mattermost/server/v8
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.0.0-20260506065351-202d125afa87"}]}]
References
- web https://nvd.nist.gov/vuln/detail/CVE-2026-7387
- web https://mattermost.com/security-updates
- web https://github.com/advisories/GHSA-6hxm-w4hv-vgvw
- web https://github.com/mattermost/mattermost/pull/36316
- web https://github.com/mattermost/mattermost/pull/36423
- web https://github.com/mattermost/mattermost/pull/36431
- web https://github.com/mattermost/mattermost/pull/36432
- web https://github.com/mattermost/mattermost/pull/36434
- web https://github.com/mattermost/mattermost/commit/1ce2484a00c9821ee19708d2c46720e4855033a9
- web https://github.com/mattermost/mattermost/commit/202d125afa87fe39611686850fd82590c99ca344
- web https://github.com/mattermost/mattermost/commit/8c72083414e675c97987374395e36d1f36b4bd8a
- web https://github.com/mattermost/mattermost/commit/a9e574a82633915f22071f0d7ca2b006f249ec2a
- web https://github.com/mattermost/mattermost/commit/d5f29c8ebbeb04460d16d9e2635ce50deeb78428
- web https://github.com/mattermost/mattermost/releases/tag/v10.11.16
- web https://github.com/mattermost/mattermost/releases/tag/v11.5.5
- web https://github.com/mattermost/mattermost/releases/tag/v11.6.2
- web https://github.com/mattermost/mattermost/releases/tag/v11.7.0