{"cve":"CVE-2026-53551","nvd":{"published":"2026-07-31T20:16:51.697","modified":"2026-09-08T20:51:43.490","status":"Deferred","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_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","score":6.9},"cvss_v3":null,"cwes":["CWE-20"],"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"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:47:10.050265369+00:00"},"epss":{"cve":"CVE-2026-53551","score":0.00737,"percentile":0.54505,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-qj55-47fp-p62j","url":"https://osv.dev/vulnerability/GHSA-qj55-47fp-p62j","summary":"free5GC AUSF: null byte injection in supiOrSuci causes HTTP 500 internal service failure","modified":"2026-08-18T15:10:46.494283172Z","packages":[{"ecosystem":"Go","name":"github.com/free5gc/free5gc","purl":"pkg:golang/github.com/free5gc/free5gc","ranges":["<4.2.2"],"fixed":["4.2.2"]},{"ecosystem":"Go","name":"github.com/free5gc/ausf","purl":"pkg:golang/github.com/free5gc/ausf","ranges":["<1.4.5"],"fixed":["1.4.5"]}]},{"id":"GO-2026-6161","url":"https://osv.dev/vulnerability/GO-2026-6161","summary":"free5GC AUSF: null byte injection in supiOrSuci causes HTTP 500 internal service failure in github.com/free5gc/ausf","modified":"2026-08-18T15:00:17.524403027Z","packages":[{"ecosystem":"Go","name":"github.com/free5gc/ausf","purl":"pkg:golang/github.com/free5gc/ausf","ranges":["<1.4.5"],"fixed":["1.4.5"]},{"ecosystem":"Go","name":"github.com/free5gc/free5gc","purl":"pkg:golang/github.com/free5gc/free5gc","ranges":["<4.2.2+incompatible"],"fixed":["4.2.2+incompatible"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}