CVE-2026-53551
This causes Go's net/url.Parse() to fail, returning HTTP 500 "System failure" and leaking internal stack traces.
Does this matter?
Lower severity and a low EPSS score (0.55%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 4.0
- 6.9 MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.55% probability · 44th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-20
- Source
- security-advisories@github.com
References
- https://github.com/free5gc/ausf/commit/bfc4a10094dbacbd862baa4686829f3fcc06ce1e
- https://github.com/free5gc/ausf/pull/61
- https://github.com/free5gc/ausf/releases/tag/v1.4.5
- https://github.com/free5gc/free5gc/issues/1048
- https://github.com/free5gc/free5gc/releases/tag/v4.2.2
- https://github.com/free5gc/free5gc/security/advisories/GHSA-qj55-47fp-p62j
- https://github.com/free5gc/free5gc/security/advisories/GHSA-qj55-47fp-p62j
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.