CVE-2026-118549

Drupal AI Markdown link validation can permit cross-site scripting

Drupal maintainers · AI module Markdown sanitization service

First documented disclosure · Review checkpoint

Summary

Markdown links can bypass an AI content sanitization service.

Severity and exploitation evidence

Unknown · numeric CVSS score not recorded. Severity source.

Exploitation not established: Drupal labels exploitation theoretical; reviewed sources establish neither malicious exploitation nor a confirmed victim.

Exploitation evidence source

Technical severity is not a measure of observed attacks or of risk to your deployment. Attempts, demonstrations, and successful compromise retain the qualifications in the source.

How the weakness works

The module insufficiently validates Markdown links under certain conditions.

Conditions required

An affected consumer renders attacker-influenced Markdown through the service; Drupal’s risk vector specifies no authenticated attacker requirement.

Potential impact

Cross-site scripting in the rendered page context.

Affected versions and configurations

AI module before 1.4.11, or 1.5.0 through 1.5.1.

Fix and mitigation status

AI 1.4.11 and 1.5.2; unsupported 1.3.x must move to a supported fixed branch.

Practical next steps

Upgrade to the fixed supported branch. Audit consumers of the Markdown sanitization service.

Operating lesson

Validate link destinations and rendering semantics, not just visible text.

Evidence and limits

The vendor advisory was public 2026-10-28; October 30 is later CNA publication. Drupal rates this Critical 15/25 under its own risk system, not CVSS; no numeric CVSS is inferred. This Markdown-link issue is separate from the HTML-rendering, HTMX and chatbot advisories.

Sources