Path Traversal in Template Upload Allows Uploading Files Outside Target Directory

Summary

Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2 fails to sanitize path traversal sequences in template file destination paths, which allows a system admin to perform path traversal attacks via malicious path components, potentially enabling malicious file placement outside intended directories.

Timeline

1. Aug 21, 2025, 7:51 AM UTCCVE published
2. Aug 21, 2025, 2:50 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Aug 21, 2025, 2:50 PM UTCRecord last updated

Affected versions

• Mattermost Mattermost

  From 10.8.0 · through 10.8.3; From 10.5.0 · through 10.5.8; From 9.11.0 · through 9.11.17; From 10.9.0 · through 10.9.2

• github.com/mattermost/mattermost-serverGo

  From 10.8.0 · fixed in 10.8.4

• github.com/mattermost/mattermost-serverGo

  From 10.5.0 · fixed in 10.5.9

• github.com/mattermost/mattermost-serverGo

  From 9.11.0 · fixed in 9.11.18

• github.com/mattermost/mattermost-serverGo

  From 10.9.0 · fixed in 10.9.3

• github.com/mattermost/mattermost/server/v8Go

  fixed in 8.0.0-20250708065844-b38e2eccda18

• github.com/mattermost/mattermost-server/v5Go

  through 5.39.5

• github.com/mattermost/mattermost-server/v6Go

  through 6.7.2

• github.com/mattermost/mattermost-serverGo

  From 9.11.0+incompatible · fixed in 9.11.18+incompatible; From 10.5.0+incompatible · fixed in 10.5.9+incompatible; From 10.8.0+incompatible · fixed in 10.8.4+incompatible; From 10.9.0+incompatible · fixed in 10.9.3+incompatible

• github.com/mattermost/mattermost-server/v5Go

  All versions

• github.com/mattermost/mattermost-server/v6Go

  All versions

References 1