CVE-2026-55784 - free5GC AUSF authentication contexts can be overwritten by concurrent requests for the same SUPI

CVE-2026-55784 - free5GC AUSF authentication contexts can be overwritten by concurrent requests for the same SUPI

https://cvefeed.io/rssfeed/latest.atom / Sat, 08/29/2026 - 01:28
CVE ID :CVE-2026-55784
Published : Aug. 28, 2026, 10:23 p.m. | 7 minutes ago
Description :free5GC is an open-source implementation of the 5G core network. In version 1.4.4 and earlier, the AUSF component stores per-subscriber authentication state in a global sync.Map named AUSFContext.UePool in internal/context/context.go, keyed only by SUPI. Every request handled by internal/sbi/processor/ue_authentication.go creates an AusfUeContext, and AddAusfUeContextToPool executes ausfContext.UePool.Store(ausfUeContext.Supi, ausfUeContext), unconditionally replacing the active context for that SUPI. An attacker with access to the AUSF SBI/N12 interface can send concurrent POST /nausf-auth/v1/ue-authentications requests for the same target SUPI, causing all attempts to share one logical authentication context URL while K_aut, XRES, and EapID are repeatedly overwritten. A valid EAP-AKA' response for an earlier challenge is then checked against the latest context, causing AT_MAC verification to fail and denying authentication to the selected subscriber while the request flood continues. No fixed version is available as of this review.
Severity: 0.0 | NA
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