---
id: CVE-2026-61520
title: Simple Machines Forum SSRF via image proxy
summary: >-
  Simple Machines Forum 2.1 prior to commit b4d23df (fixed in 2.1.8) and 3.0
  prior to commit 4bf35cf contains a server-side request forgery vulnerability
  in the image proxy that allows authenticated attackers to trigger internal
  HTTP reque…
severity: high
cvss: 7.7
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N'
cvssSource: cna
cwe:
  - CWE-918
vendor: SimpleMachines
product: SMF
affected:
  - SMF >= 2.1.0 < 2.1.8
  - SMF >= 3.0.0-alpha.1 <= 3.0.0-alpha.4
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-07-15T13:20:14.309005Z'
published: '2026-07-14'
updated: '2026-10-29'
sourceUpdated: '2026-10-29T21:16:07.731Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-61520'
references:
  - url: >-
      https://github.com/SimpleMachines/SMF/commit/4bf35cf9e45573a5f55a6f52995086c1da89c096
    label: Patch Commit (v3.0)
  - url: >-
      https://github.com/SimpleMachines/SMF/commit/b4d23dfd74a511587c605f9d294cefc3a75b4b26
    label: Patch Commit (v2.1)
  - url: >-
      https://www.vulncheck.com/advisories/simple-machines-forum-ssrf-via-image-proxy
tags:
  - cve.org
epss: 0.00437
epssPercentile: 0.38112
ingestedAt: '2026-11-03T08:39:35.571Z'
---

## Overview

Simple Machines Forum 2.1 prior to commit b4d23df (fixed in 2.1.8) and 3.0 prior to commit 4bf35cf 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

- `SMF >= 2.1.0 < 2.1.8`
- `SMF >= 3.0.0-alpha.1 <= 3.0.0-alpha.4`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.