dbcve.org
Server-Side Request Forgery (SSRF)Weakness · CWE-918

CVE-2026-61520

HIGH · 7.7 CVSS v3.1 Published 2026-07-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
83/100
Remediation priority · High
Remotely reachable Zero-click 5 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

Simple Machines Forum contains an SSRF vulnerability in its image proxy where BBCode image tags accept attacker-controlled URLs that are fetched without validating resolved destination IPs against private ranges, loopback (127.0.0.0/8), or link-local addresses (169.254.0.0/16). The forum's automatic HMAC signature generation for proxy requests allows authenticated attackers to craft valid signed requests targeting internal services such as cloud metadata endpoints (169.254.169.254), internal web apps, and container networks.

MitigationUpgrade to SMF 2.1 (commit 4bf35cf or later) or SMF 3.0 (commit b4d23cf or later) which implements proper IP validation. Alternatively, restrict outbound traffic from the proxy server to internal IP ranges at the network perimeter.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify SMF version
    Check the version.php file in the SMF root directory, or look at the footer of the forum pages, or query the database settings table for 'smfVersion'
    Affected if version is before SMF 2.1 (commit 4bf35cf) or SMF 3.0 (commit b4d23cf)
  2. Verify image proxy is enabled
    Navigate to Admin > Server Settings > General in the SMF admin panel, or inspect the $modSettings['enableProxy'] value in the database
    Affected if the image proxy setting is enabled ($modSettings['enableProxy'] = 1)
  3. Confirm BBCode image tags are permitted
    Check Admin > Posts and Topics > Bulletin Board Code > ensure [img] BBC is not disabled, or inspect $modSettings['bbc']['img'] in settings
    Affected if the [img] BBCode tag is enabled in the forum's BBC settings
  4. Check for proxy request signing
    Examine the source code in Sources/ProxyServer.php or similar proxy handling files for HMAC signature generation logic without IP validation
    Affected if the proxy code lacks validation of resolved IPs against 127.0.0.0/8, 169.254.0.0/16, and private IP ranges

A user is affected if running an unpatched SMF version with the image proxy enabled and [img] BBCode tags allowed, allowing an authenticated attacker to proxy requests to internal services via crafted URLs.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to SMF 2.1 (commit 4bf35cf or later) or SMF 3.0 (commit b4d23cf or later) which implements proper IP validation. Alternatively, restrict outbound traffic from the proxy server to internal IP ranges at the network perimeter.

Recommended fix Moderate confidence

SMF 2.1: Any release version containing commit 4bf35cf or later; SMF 3.0: Any release version containing commit b4d23df or later

  1. Identify the currently installed Simple Machines Forum version (2.1.x or 3.0.x) by checking the version.php file in the SMF root directory
  2. For SMF 2.1.x: Upgrade to version that includes commit 4bf35cf or later (check SMF 2.1 release notes for the corresponding version number)
  3. For SMF 3.0.x: Upgrade to version that includes commit b4d23df or later (check SMF 3.0 release notes for the corresponding version number)
  4. After upgrade, verify the image proxy now properly validates resolved IP addresses against private ranges (127.0.0.0/8, 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 169.254.0.0/16) before fetching
  5. Test that BBCode image tags with internal URLs (e.g., http://localhost, http://169.254.169.254) are blocked by the image proxy
  6. Review and test any custom modifications or themes for compatibility with the updated version
Caveat Review custom themes, mods, and integrations for compatibility with the new version before deploying to production

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,224.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-61520 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-61520 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data