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TI-2026-40273 Aliases CVE-2026-55784GHSA-334q-h5g3-fpxv

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

Priority HIGH 72CWE-362Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · None · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00419 36th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
free5gcfree5gcup to 1.4.4—No fix listedCNA
—github.com/free5gc/ausf (Go)up to 1.4.4—No fix listedGHSA-334q-h5g3-fpxv
  • free5gc Vendorfree5gc Affected up to 1.4.4 Fixed in — No fix listed CNA
  • github.com/free5gc/ausf (Go) Vendor— Affected up to 1.4.4 Fixed in — No fix listed GHSA-334q-h5g3-fpxv

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-55784
  2. 2026-10-03 Alias added: GHSA-334q-h5g3-fpxv

References

Other 2

  • TI-2026-32298 Incorrect authorization in free5gc CVSS 3.1CRITICAL 10.0
  • TI-2026-32297 free5GC: SMF UPI management interface lacks auth middleware; unauthenticated topology read/write requests reach handlers CVSS 3.1CRITICAL 10.0
  • TI-2026-32295 free5GC: NEF nnef-oam route group is unauthenticated; no-token requests reach the OAM handler CVSS 3.1CRITICAL 10.0
  • TI-2025-39412 free5gc v4.1.0 and before is vulnerable to Buffer Overflow. CVSS 3.1CRITICAL 9.8
  • TI-2026-32294 Missing authorization in free5gc CVSS 3.1CRITICAL 9.4
  • TI-2026-32283 Missing authorization in free5gc CVSS 3.1CRITICAL 9.4
See all 86 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences