CVE-2026-61520: Simplemachines Smf

High severity, CVSS 7.7. EPSS: 0.4% chance of exploitation in the next 30 days.

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.

Affected products

• Simplemachines Smf: from 2.1.0, before 2.1.7 (fixed in 2.1.7)

Published 2026-07-14. Last modified 2026-07-15.