CVE-2026-25776 Sixapart CVE debrief

Who should care

Administrators and users of Movable Type, especially those with sensitive data or high-traffic websites, should be aware of this vulnerability and take immediate action to mitigate the risk. This includes reviewing compensating controls, monitoring for suspicious activity, and implementing additional security measures as needed.

Technical summary

The vulnerability is caused by a code injection issue in Movable Type, which allows an attacker to execute arbitrary Perl script. This could lead to unauthorized access, data breaches, and other malicious activities. The vulnerability has a CVSS score of 9.3 and is classified as CRITICAL. Affected versions of Movable Type include 8.0.2-8.0.10, 8.8.0-8.8.3, 9.0.1-9.0.7, and 9.1.0. It is essential to apply the latest security patches and updates provided by Six Apart Ltd. to prevent exploitation.

Defensive priority

High

Recommended defensive actions

• Apply the latest security patches and updates provided by Six Apart Ltd.
• Restrict access to sensitive areas of the Movable Type installation
• Monitor for suspicious activity and implement additional security measures as needed
• Consider implementing a web application firewall (WAF) to detect and prevent attacks
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The vulnerability is confirmed by the National Vulnerability Database (NVD) and has a CVSS score of 9.3. The affected versions of Movable Type include 8.0.2-8.0.10, 8.8.0-8.8.3, 9.0.1-9.0.7, and 9.1.0. Additional verification is recommended to confirm the presence of vulnerable versions in managed environments. It is essential to review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.

Official resources