Discourse: Cross-site backup access via path traversal in multisite local backups
Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.4, 2026.3.0-latest to before 2026.3.1, and 2026.4.0-latest to before 2026.4.1, a path traversal vulnerability in Discourse backup handling could allow an authenticated administrator on one site in a multisite deployment to access backup files belonging to another site when backups are stored locally. In affected configurations, an admin on Site A could potentially retrieve sensitive backup data from Site B (same host, multisite) by crafting a backup download request with a traversal payload. This issue has been patched in versions 2026.1.4, 2026.3.1, 2026.4.1, and 2026.5.0-latest.1.
Problem Types
| Type | CWE ID | Description |
|---|
| CWE | CWE-22 | CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') |
Type: CWE
Description: CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Metrics
| Version | Base score | Base severity | Vector |
|---|
| 3.1 | 6.8 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N |
Version: 3.1
Base score: 6.8
Base severity: MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N