CVE intelligence and bounded remediation
CVE-2025-13870 — Mattermost Mattermost Server security vulnerability
Mattermost versions 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to validate the user permission when accessing the files and subscribing to the block in Boards, which allows an authenticated user to access other board files and was able to subscribe to the block from other boards that the user does not have access to
- Severity
- Medium
- CVSS
- 4.3 (3.1)
- Published
- 2025-12-02
- CISA KEV
- Not currently listed
- Ecosystem
- software/application
- Weaknesses
- CWE-306
Affected products
- mattermost / mattermost_server
Showing 1 representative product identities from 2 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.
Matched remediation archetype
Authentication bypass and missing authentication
This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.
Check exposure
- Map every affected endpoint and protocol path, including alternate ports, legacy routes, recovery flows, service accounts, and machine-to-machine access.
- Confirm which deployments enable the affected authentication mode and whether the interface is reachable from untrusted networks.
- Review session, token, credential, and proxy trust configuration without attempting account takeover.
Remediate safely
- Apply the supported fix and centralize fail-closed authentication before protected request handling.
- Remove default or embedded credentials, rotate affected secrets and sessions, and bind authentication decisions to the intended audience and channel.
- Add negative tests for alternate routes, malformed or absent credentials, recovery flows, and proxy-derived identity.
Authoritative sources
Complete CVE record and remediation plan
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