free5GC has Improper Input Validation in UDM, Leading to Information Exposure

Vulnerability Description

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 ueId parameter, triggering internal URL parsing errors (net/url: invalid control character). This exposes system implementation details and can aid in service fingerprinting. All deployments of free5GC using the UDM Nudm_UECM service may be affected. free5gc/udm pull request 76 contains a fix for the issue. No direct workaround is available at the application level. Applying the official patch is recommended.

References

• https://github.com/free5gc/free5gc/security/advisories/GHSA-pwxh-4qh4-hgpq
• https://github.com/free5gc/free5gc/issues/751
• https://github.com/free5gc/free5gc/issues/76
• https://github.com/free5gc/udm/commit/504b14458d156558b3c0ade7107b86b3d5e72998