Vulnerability · Published Feb 24, 2026 · Assigned by GitHub_M

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

Medium 6.6

In plain English

A medium-severity improper input validation in udm from free5gc. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 47% of all known vulnerabilities).

Severity (CVSS 4.0)6.6Medium

Exploit odds (30 days)0.6%top 52.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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 (as reported)

Vendor	Product	Versions
free5gc	udm	<= 1.4.1

Weakness: CWE-20 · 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/E:U

References

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