What’s Vulnerable › Vulnerabilities

CVE-2026-27642: free5GC has Improper Input Validation in UDM UEAU Service

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-02-24 · updated 2026-06-17
• Weakness: CWE-20

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 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: through 1.4.1

References

• https://github.com/free5gc/free5gc/issues/749
• https://github.com/free5gc/free5gc/security/advisories/GHSA-h4wg-rp7m-8xx4
• https://github.com/free5gc/udm/commit/a7af2321ddea6368c43835f90f6d1b9d67dd2ea1
• https://github.com/free5gc/udm/pull/75

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