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.
https://github.com/free5gc/udm/commit/504b14458d156558b3c0ade7107b86b3d5e72998
https://github.com/free5gc/free5gc/security/advisories/GHSA-pwxh-4qh4-hgpq
Published: 2026-02-24
Updated: 2026-02-24
Base Score: 5
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:N
Severity: Medium
Base Score: 5.3
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Severity: Medium
Base Score: 8.7
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Severity: High
EPSS: 0.00226