CVE-2026-27642: FREE5GC Udm

High severity, CVSS 7.5. EPSS: 0.7% chance of exploitation in the next 30 days.

free5gc UDM provides Unified Data Management (UDM) for free5GC, an open-source project for 5th generation (5G) mobile core networks. In versions up to and including 1.4.1, remote attackers can inject control characters (e.g., %00) into the supi parameter, triggering internal URL parsing errors (net/url: invalid control character). This exposes system-level error details and can be used for service fingerprinting. All deployments of free5GC using the UDM Nudm_UEAU service may be affected. free5gc/udm pull request 75 contains a fix for the issue. No direct workaround is available at the application level. Applying the official patch is recommended.

Affected products

• FREE5GC Udm: up to and including 1.4.1

Published 2026-02-24. Last modified 2026-06-17.