CVE-2026-12108 is a stored cross-site scripting vulnerability in the Highlighting Code Block WordPress plugin by looswebstudio. The flaw exists due to improper neutralization of input during web page generation, specifically in admin settings, allowing authenticated administrators to inject arbitrary scripts. This vulnerability affects multi-site WordPress installations and installations with unfiltered_html disabled, impacting all plugin versions up to and including 2.2.0. The CVSS 3.1 vector indicates network attack vector, high attack complexity, high privileges required, no user interaction, scope changed, and low impact on confidentiality and integrity, with no impact on availability.

An authenticated attacker with administrator-level permissions can inject malicious scripts into pages via the plugin's admin settings. These scripts execute in the context of users visiting the injected pages, potentially leading to unauthorized actions or data exposure. The vulnerability is limited to multi-site WordPress setups or those with unfiltered_html disabled, reducing the attack surface. There is no indication of known exploits in the wild.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, restrict administrator access to trusted users only and consider disabling or removing the Highlighting Code Block plugin in multi-site environments or where unfiltered_html is disabled. Monitor vendor channels for updates and apply patches promptly once available.