Broken Link Notifier <= 1.3.0 - Unauthenticated Server-Side Request Forgery
Strategic Overview
- Status
- Patched in 1.3.1
- Affected Plugin
- Broken Link Notifier
- Affected Version
<= 1.3.0- CVSS
- 7.2High
- Weakness type
- CWE-918 · Server-Side Request Forgery (SSRF)
- CVE
CVE-2025-6851
At a glance
CVE-2025-6851 is a high-severity Server-Side Request Forgery (SSRF) vulnerability in the Broken Link Notifier WordPress plugin, affecting versions <= 1.3.0. It carries a CVSS score of 7.2 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 1.3.1; sites on affected versions should update now. Disclosed July 2025, reported by Jonas Benjamin Friedli.
Vulnerability Overview
The Broken Link Notifier plugin for WordPress is vulnerable to Server-Side Request Forgery in all versions up to, and including, 1.3.0 via the ajax_blinks() function which ultimately calls the check_url_status_code() function. This makes it possible for unauthenticated attackers to make web requests to arbitrary locations originating from the web application and can be used to query and modify information from internal services.
Technical Analysis
The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user.
CWE-918: Server-Side Request Forgery (SSRF)
Broken Link Notifier <= 1.3.0 carries this weakness at ajax_blinks(), and reaching it takes no account at all. Server-side request forgery means the application fetches a URL supplied by the caller, turning the server into a proxy for requests the attacker could not make directly.
The request originates from inside the hosting network, which is how these flaws reach cloud metadata endpoints, internal admin panels and services that trust local traffic. For Broken Link Notifier the fix is 1.3.1: builds <= 1.3.0 are affected, anything from 1.3.1 onward is not.
Remediation
Update to version 1.3.1, or a newer patched version
How does WordSec protect against this?
Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Broken Link Notifier 1.3.1 closes this, and updating the plugin is the step that ends it.
- Firewall
- Login Security
- Alerts
External References
Related records
Other vulnerabilities in Broken Link Notifier
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