Vulnerability in Mattermost (CVE-2026-13417)
Summary
Vulnerability in Mattermost (CVE-2026-13417). Risk of unauthorized operations or information disclosure. Exploitable via fields.properties.
Original description
The description as published by the source.
Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to validate the type of fields.properties on block creation which allows an authenticated user with editor access to a board to crash the Boards plugin worker and trigger a denial of service via a child block whose fields.properties is a non-object value. Mattermost Advisory ID: MMSA-2026-00710
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-2026-13417 has been found in Mattermost.
Attackers can target a specific entry point like fields.properties over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.3/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Mattermost CVE-2026-13417" on the vendor's site.
CVE-2026-13417 (Mattermost) — CWE-754 / CVSS v3 4.3
Attack vector: remote (network-reachable) / no user interaction
Attack surface: fields.properties
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-754) exists in Mattermost. Attackers reach the vulnerable code path via fields.properties.
Check the vendor advisory for the affected versions of Mattermost. Attack surface: fields.properties.
Severity: Medium (CVSS 4.3/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
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 'Mattermost' . 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 'Mattermost' . | 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
Mattermostを grep し、稼働しているサービス・バージョンを把握する。 -
2Post-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。
References
- patch responsibledisclosure@mattermost.com
- web nvd.nist.gov
- web github.com