Path traversal in Discourse - #VU165856
Published: November 11, 2026
Vulnerability identifier: #VU165856
CSH Severity: Low
CVSS v4: 8.5 [CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-22
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote privileged user to read or overwrite files outside the uploads directory, including server configuration files.
The vulnerability exists due to path traversal in Discourse's restored upload records when processing backups on sites with allow_restore enabled. A remote privileged user can restore a crafted backup containing upload paths outside the uploads directory to cause Discourse to read or write files elsewhere on the server.
Affected software
Discourse
Remediation
Install security update from vendor's website.
Discourse - addressed in versions 2026.7.5, 2026.9.2, 2026.10.1