free5GC AUSF authentication contexts can be overwritten by concurrent requests for the same SUPI (CVE-2026-55784) | HOL Guard CVE

High · CVSS 7.5CVE-2026-55784GHSA-334Q-H5G3-FPXV

free5GC AUSF authentication contexts can be overwritten by concurrent requests for the same SUPI

Answer in brief

CVE-2026-55784 records a High severity (CVSS 7.5) vulnerability in free5GC AUSF authentication contexts can be overwritten by concurrent requests for the same SUPI. The current sources do not mark it as known exploited. The current feed maps free5gc/free5gc (generic), github.com/free5gc/ausf (go). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 28, 2026Updated Aug 28, 2026Source checked Aug 28, 2026First seen by HOL Aug 28, 2026Material review Aug 28, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.5
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Not reported

Why this deserves its current priority

CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps free5gc/free5gc (generic), github.com/free5gc/ausf (go). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
free5gc/free5gcgeneric	<= 1.4.4	Not reported
github.com/free5gc/ausfgo	<=1.4.4	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for free5gc/free5gc, github.com/free5gc/ausf.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Aug 28, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 28, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 28, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.