SEPTEMBER 19, 2026
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Case File

CVE-2026-53551

MEDIUM · CVSS 6.9 EPSS 0.43% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-07-31 · Last synced 2026-08-30

CyberRota Analysis

AI-Generated

The free5GC AUSF (Authentication Server Function) prior to version 1.4.5 is vulnerable due to improper validation of the supiOrSuci field in UE authentication requests, allowing unauthenticated attackers to exploit null bytes and control characters. This can lead to a denial of service for all subscribers by triggering HTTP 500 errors and leaking internal stack traces. Organizations using free5GC should prioritize upgrading to version 1.4.5 to mitigate this risk.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-53551
Severity
MEDIUM
CVSS
6.9
EPSS
0.43%

Original NVD 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.