Broken Link Checker - RCE (CVE-2026-18937)

CVE-2026-18937 is a critical vulnerability in the Broken Link Checker WordPress plugin versions before 2.4.12. On sites using plain permalinks, unauthenticated attackers can manipulate PHP global variables through query parameters and, when a classic non-block theme is active, potentially execute arbitrary code on the server.

CrowdSec has been tracking this vulnerability and its exploits since 22nd of October 2026.

Data from the CrowdSec community indicates that exploitation of CVE-2026-18937 is highly selective and intelligence-driven. Threat actors use advanced reconnaissance and carefully choose their targets, often as part of sophisticated campaigns or advanced persistent threat operations. Data from the CrowdSec community also indicates a gradual decrease in attacks targeting CVE-2026-18937. While still present in the wild, exploitation levels have dropped noticeably week-over-week. This may signal that the vulnerability is becoming less relevant or that defenses are improving fast enough for attackers to lose interest.

Attackers target the WordPress root endpoint (/) with crafted query parameters that overwrite widget and sidebar globals, invoking system to execute a command such as id.