Server-Side Request Forgery (SSRF) in Discourse - #VU166165
Published: November 13, 2026
Vulnerability identifier: #VU166165
CSH Severity: Low
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-918
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote privileged user to read arbitrary URLs from the server and potentially disclose sensitive information.
The vulnerability exists due to server-side request forgery in Discourse's animated GIF detection job when processing upload records restored from a crafted backup on sites with allow_restore enabled. A remote privileged user can supply a backup containing crafted upload records to bypass the usual SSRF protections and access resources outside the upload store.
Affected software
Discourse
Remediation
Install security update from vendor's website.
Discourse - addressed in versions 2026.7.5, 2026.9.2, 2026.10.1