CVE-2026-18937

Broken Link Checker < 2.4.12 - Unauthenticated Remote Code Execution

2026-08-21 00:00
Jakub Herman

Strategic Overview

Status
Patched in 2.4.12
Affected Plugin
Broken Link Checker
Affected Version
< 2.4.12
CVSS
9.8Critical
Weakness type
CWE-94 · Improper Control of Generation of Code ('Code Injection')
CVE
CVE-2026-18937
View all Broken Link Checker vulnerabilities

At a glance

CVE-2026-18937 is a critical-severity Improper Control of Generation of Code ('Code Injection') vulnerability in the Broken Link Checker WordPress plugin, affecting versions < 2.4.12. It carries a CVSS score of 9.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 2.4.12; sites on affected versions should update now. Disclosed August 2026, reported by Jakub Herman.

Vulnerability Overview

The Broken Link Checker plugin for WordPress is vulnerable to Remote Code Execution in all versions up to 2.4.12. This is due to insufficient validation of user supplied input before it is executed. This makes it possible for unauthenticated attackers to execute arbitrary code on the server.

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. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.

CWE-94: Improper Control of Generation of Code ('Code Injection')

Reaching this weakness in Broken Link Checker < 2.4.12 takes no account at all. Code injection means input from a request reaches a language construct that evaluates code, so the attacker's text is executed rather than treated as data.

The injected code runs with the web server's privileges, giving the attacker the same access to the database and filesystem as WordPress itself. For Broken Link Checker the fix is 2.4.12: builds < 2.4.12 are affected, anything from 2.4.12 onward is not.

Remediation

Update to version 2.4.12, 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. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: Broken Link Checker 2.4.12 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Scanner
  • Login Security

External References

https://www.cve.org/CVERecord?id=CVE-2026-18937https://www.wordfence.com/threat-intel/vulnerabilities/id/fd3b95ce-3051-4b41-8bf4-362fa6be6ce5https://nvd.nist.gov/vuln/detail/CVE-2026-18937

Related records

Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C