CVE-2026-53421 Apache Software Foundation CVE debrief

Who should care

Users of Apache Syncope versions 3.0.0-M0 through 3.0.16, 4.0.0-M0 through 4.0.6, and 4.1.0-M0 through 4.1.1 should upgrade to version 4.0.7 or 4.1.2 to address the vulnerability. This includes administrators, security teams, and operators responsible for maintaining and securing Apache Syncope deployments.

Technical summary

The vulnerability exists in the connector subsystem of Apache Syncope, allowing an administrator with adequate entitlements to execute remote code by leveraging the Groovy script capabilities of scripted connectors (REST and SQL). This issue affects multiple versions of Apache Syncope, specifically 3.0.0-M0 through 3.0.16, 4.0.0-M0 through 4.0.6, and 4.1.0-M0 through 4.1.1. The fix involves upgrading to version 4.0.7 or 4.1.2, which hardens the Groovy security sandbox.

Defensive priority

High priority should be given to upgrading Apache Syncope to version 4.0.7 or 4.1.2, as the vulnerability allows for remote code execution.

Recommended defensive actions

• Upgrade Apache Syncope to version 4.0.7 or 4.1.2
• Review and restrict administrator entitlements
• Monitor for suspicious activity in the connector subsystem
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE record was published on 2026-07-20T15:16:43.117Z and was last modified on 2026-07-21T16:17:15.043Z. The NVD entry is currently Undergoing Analysis. This CVE is related to an Improper Isolation or Compartmentalization vulnerability in Apache Syncope, which allows an administrator with adequate entitlements to achieve remote code execution through the connector subsystem by relying on scripted connectors' (REST and SQL) capability to run Groovy scripts. Users are recommended to upgrade to version 4.0.7 or 4.1.2, which fix this issue by hardening the Groovy security sandbox. The affected versions include 3.0.0-M0 through 3.0.16, 4.0.0-M0 through 4.0.6, and 4.1.0-M0 through 4.1.1.

Official resources