Cryptographic Authentication Vulnerability in free5GC AUSF Component

CVE-2026-55785

What is CVE-2026-55785?

The AUSF component of free5GC, an open-source implementation of the 5G core network, has a vulnerability that allows for insecure cryptographic authentication comparisons. In versions prior to 1.4.5, this issue arises from the use of consistent equality helpers, specifically in the ue_authentication.go file. The Auth5gAkaComfirmRequestProcedure improperly compares authentication values using methods that can lead to mismatch-dependent timing variations. Although practical exploitation as a remote timing oracle was not demonstrated due to HTTP/SBI timing unpredictability, the INFO-level logging exposes sensitive authentication information to log collectors, operators, or other monitoring processes, increasing the risk of data exposure. This critical issue has been addressed in the release of version 1.4.5.

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