CVE-2026-53551

Description

free5GC is an open-source implementation of the 5G core network. Prior to 1.4.5, the free5GC AUSF (Authentication Server Function) does not validate the supiOrSuci field in UE authentication requests. Null bytes (\x00) and other control characters pass through JSON parsing unchanged and are forwarded to the UDM in an unescaped URL path. This causes Go's net/url.Parse() to fail, returning HTTP 500 "System failure" and leaking internal stack traces. An unauthenticated attacker can trigger this at scale causing denial of service for all subscribers attempting authentication through the affected AUSF. This vulnerability is fixed in 1.4.5.

References

https://github.com/free5gc/free5gc/security/advisories/GHSA-qj55-47fp-p62j

https://github.com/free5gc/free5gc/releases/tag/v4.2.2

https://github.com/free5gc/free5gc/issues/1048

https://github.com/free5gc/ausf/releases/tag/v1.4.5

https://github.com/free5gc/ausf/pull/61

https://github.com/free5gc/ausf/commit/bfc4a10094dbacbd862baa4686829f3fcc06ce1e

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

CVSS v4

EPSS