Vulnerability in Mattermost Plugins (CVE-2026-16049)
Summary
Vulnerability in Mattermost Plugins (CVE-2026-16049). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
Mattermost Plugins versions <=11.8 10.20.11 11.5.7.0 The Mattermost GitLab plugin fails to verify channel permissions when processing API requests with a caller-supplied {{post_id}}, and fails to validate the {{web_url}} parameter against the configured GitLab instance, which allows an authenticated attacker to inject bot-authored messages containing arbitrary URLs into channels they do not have access to via the {{createIssue}} and {{attachCommentToIssue}} API endpoints. Mattermost Advisory ID: MMSA-2026-00673
Source: GitHub Security Advisories (Global) 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-2026-16049 has been found in Mattermost Plugins.
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 Plugins CVE-2026-16049" on the vendor's site.
CVE-2026-16049 (Mattermost Plugins) — CWE-862 / CVSS v3 4.3
Attack vector: remote (network-reachable) / no user interaction
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-862) exists in Mattermost Plugins.
Check the vendor advisory for the affected versions of Mattermost Plugins.
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. Audit SBOM/dependencies 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
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Mattermost Plugins を使っているサービスとバージョンを洗い出す。
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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。