Vulnerability Description
Simple Machines Forum 2.1 prior to commit 4bf35cf and 3.0 prior to commit b4d23df contains a server-side request forgery vulnerability in the image proxy that allows authenticated attackers to trigger internal HTTP requests by embedding attacker-controlled URLs in BBCode image tags, which the proxy fetches without validating resolved destination IPs against private address ranges, loopback, or link-local addresses. Attackers can leverage SMF's automatic HMAC signature generation for any embedded image URL to obtain valid signed proxy requests targeting internal services such as cloud instance metadata endpoints, internal web applications, and container network services.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/SimpleMachines/SMF/commit/4bf35cf9e45573a5f55a6f52995086c1da8
- https://github.com/SimpleMachines/SMF/commit/b4d23dfd74a511587c605f9d294cefc3a75
- https://www.vulncheck.com/advisories/simple-machines-forum-ssrf-via-image-proxy
FAQ
What is CVE-2026-61520?
CVE-2026-61520 is a vulnerability with a CVSS score of 7.7 (HIGH). Simple Machines Forum 2.1 prior to commit 4bf35cf and 3.0 prior to commit b4d23df contains a server-side request forgery vulnerability in the image proxy that allows authenticated attackers to trigger...
How severe is CVE-2026-61520?
CVE-2026-61520 has been rated HIGH with a CVSS base score of 7.7/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-61520?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.