CVE-2026-55785 - free5GC AUSF uses non-constant-time authentication comparisons and logs XRES* in 5G-AKA

CVE-2026-55785 - free5GC AUSF uses non-constant-time authentication comparisons and logs XRES* in 5G-AKA

https://cvefeed.io/rssfeed/latest.atom / Sat, 08/29/2026 - 01:28
CVE ID :CVE-2026-55785
Published : Aug. 28, 2026, 10:25 p.m. | 5 minutes ago
Description :free5GC is an open-source implementation of the 5G core network. Prior to 1.4.5, the AUSF component performs cryptographic authentication comparisons in internal/sbi/processor/ue_authentication.go with ordinary equality helpers. Auth5gAkaComfirmRequestProcedure compares RES* and XRES* with strings.EqualFold and logs the expected XRES* value at INFO level before comparison. EapAuthComfirmRequestProcedure compares AT_MAC and XMAC with bytes.Equal and evaluates XRES == RES with ordinary string equality. These comparisons can return at mismatch-dependent times, although testing did not demonstrate a practical remote timing oracle because of HTTP/SBI timing noise. The INFO log exposes authentication material to operators, log collectors, sidecars, or processes able to read AUSF logs. This issue is fixed in version 1.4.5.
Severity: 0.0 | NA
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