CVE-2026-76758: Drupal Link Parser Information Disclosure

CVE-2026-76758 Overview

CVE-2026-76758 is an improper input validation issue [CWE-20] in the Drupal Link content parser contributed module. An attacker with high privileges on a network-reachable Drupal site can send crafted input that the parser fails to validate correctly. Successful exploitation impacts confidentiality and integrity of the affected site. The issue does not affect availability. Drupal published details in the Drupal Security Advisory.

Critical Impact
Authenticated attackers can abuse the Link content parser to bypass input handling assumptions and access or modify data that should be protected by module logic.

Affected Products

Drupal Link content parser contributed module
Drupal sites that install and enable the Link content parser module
Deployments exposing content-editing roles to untrusted or semi-trusted users

Discovery Timeline

2026-09-02 - CVE-2026-76758 published to NVD
2026-09-02 - Last updated in NVD database

Technical Details for CVE-2026-76758

Vulnerability Analysis

The vulnerability lives in the Link content parser, a Drupal contributed module that processes link content submitted through Drupal's content APIs. The module accepts input from authenticated users and parses it without enforcing sufficient validation of structure or contents. An attacker with existing high privileges on the site can craft input the parser accepts as trusted, then leverage the resulting parsed output to affect other content or data flows on the site.

The attack requires network access and interacts with the Drupal application over HTTP or HTTPS. No user interaction from a victim is needed. Exploitation is described as high complexity, which is consistent with an attacker needing specific site conditions or authored content to trigger the parser path. The vendor scope is unchanged, meaning the impact stays within the vulnerable Drupal application boundary.

Root Cause

The root cause is improper input validation [CWE-20] inside the Link content parser. The parser trusts input properties that should be independently validated against Drupal's content model. Because validation is incomplete, malformed or hostile link content can bypass the parser's assumptions and lead to unintended reads or writes against site content.

Attack Vector

The attacker authenticates to a Drupal site with a role that can submit or edit content processed by the Link content parser. The attacker then submits crafted link content over the network. When the module parses this content, the missing validation allows the attacker to influence the resulting data, affecting confidentiality and integrity of stored site content. Full technical detail is available in the Drupal Security Advisory.

No public proof-of-concept, exploit code, or CISA KEV listing is currently associated with this CVE. Refer to the Drupal advisory for verified exploitation prerequisites; no verified code sample is available.

Detection Methods for CVE-2026-76758

Indicators of Compromise

Unexpected modifications to link fields or link-containing content authored by privileged users
Content revisions from editor or admin accounts containing malformed link structures, unusual protocols, or oversized payloads
Error or warning entries in Drupal's watchdog log referencing the Link content parser module

Detection Strategies

Review Drupal's content revision history for anomalous edits to link-bearing entities and compare against expected editorial workflow
Enable and monitor verbose logging for the Link content parser module and forward Drupal logs to a centralized SIEM
Correlate authenticated POST and PATCH requests to content and JSON:API endpoints with subsequent parser log entries

Monitoring Recommendations

Alert on privileged Drupal accounts creating or editing link content outside normal business hours or from new IP ranges
Track the installed version of the Link content parser module across all Drupal environments and alert on unpatched instances
Baseline normal editor activity so deviations in content submission volume or structure surface quickly

How to Mitigate CVE-2026-76758

Immediate Actions Required

Consult the Drupal Security Advisory and identify every site running the Link content parser module
Upgrade the Link content parser module to the fixed release identified in the vendor advisory
Audit accounts that hold roles capable of submitting or editing link content and remove unnecessary privileges

Patch Information

Drupal published fix details in sa-contrib-2026-101. Site operators should update the Link content parser module to the version specified in that advisory using composer update for Composer-managed sites or the Drupal update UI for tarball installs. After updating, clear caches with drush cr and verify the new module version in the site's Extend administration page.

Workarounds

Temporarily disable the Link content parser module on sites that cannot be patched immediately
Restrict content-editing roles to trusted users only and remove the permission to submit content that flows through the parser
Place the Drupal administrative and editorial endpoints behind a web application firewall or VPN to reduce exposure

bash

# Update the Link content parser module on a Composer-managed Drupal site
composer update drupal/link_content_parser --with-dependencies
drush updatedb
drush cache:rebuild
drush pm:list --status=enabled | grep link_content_parser