CVE-2026-27642
free5GC has Improper Input Validation in UDM UEAU Service
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.
| CWE | CWE-20 |
| Vendor | free5gc |
| Product | udm |
| Published | Feb 24, 2026 |
| Last Updated | Feb 26, 2026 |
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