Admin RCE via prepackaged plugins by way of misconfigured imports directory

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

• mattermost mattermost server9.11.0 and later · before 9.11.18
• mattermost mattermost server10.5.0 and later · before 10.5.9
• mattermost mattermost server10.8.0 and later · before 10.8.4
• mattermost mattermost server10.9.0 and later · before 10.9.4
• mattermost mattermost server10.10.0 and later · before 10.10.2

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Mattermost). Independent of NVD's CPE analysis and usually ahead of it.

• Mattermost Mattermost

  • 10.11.0, 10.8.4, 10.5.9, 9.11.18, 10.10.2, 10.9.4not affected
  • 10.8.0 and later · up to and including 10.8.3affected · semver
  • 10.5.0 and later · up to and including 10.5.8affected · semver
  • 9.11.0 and later · up to and including 9.11.17affected · semver
  • 10.10.0 and later · up to and including 10.10.1affected · semver
  • 10.9.0 and later · up to and including 10.9.3affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Other highest-scoring records for the same primary product.

• CVE-2026-4858Path traversal in integration action URL leading to arbitrary API execution via system admin’s auth token.
  39Monitor
• CVE-2025-12421Account Takeover via Code Exchange Endpoint
  39Monitor
• CVE-2025-12419Account takeover on OAuth/OpenID-enabled servers
  39Monitor
• CVE-2025-4981Path Traversal Leading to RCE by Any Authenticated Mattermost User
  39Monitor
• CVE-2023-6458Client side path traversal due to lack of route parameters validation
  39Monitor
• CVE-2017-18920An issue was discovered in Mattermost Server before 3.6.2.
  39Monitor

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Root cause

A user-supplied file name is joined with the allowed directory, but the result is never checked to confirm it is still inside that directory.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

1const file = path.join(ROOT, req.query.name);2res.sendFile(file);

1const file = path.resolve(ROOT, req.query.name);2if (!file.startsWith(ROOT + path.sep)) {3  return res.sendStatus(400);4}5res.sendFile(file);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.