SSRF in Simplemachines Smf
CVE-2026-61520
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.
Vulnerability class: SSRF (Server-Side Request Forgery)
EPSS: 0.004 (36.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.7 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N.
Affected products
- Simplemachines Smf — versions 2.1.0, 4bf35cf9e45573a5f55a6f52995086c1da89c096, 3.0.0
Weakness classification (CWE)
References
- Patch Commit (v2.1) (patch)
- Patch Commit (v3.0) (patch)
- disclosure@vulncheck.com (third-party-advisory)
Frequently asked questions
- What is CVE-2026-61520?
- CVE-2026-61520 is a high-severity vulnerability in Simplemachines Smf, classified under Server-Side Request Forgery (SSRF). CVSS score: 7.7/10. Published 2026-07-14.
- How severe is CVE-2026-61520?
- High severity. CVSS v3 base score is 7.7 out of 10.