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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-55784: 0.42% estimated exploitation activity in the next 30 days; percentile 36.24 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The AUSF component of free5GC stores per-subscriber authentication state in a global sync.Map keyed only by SUPI. Every incoming authentication request creates a new AusfUeContext and stores it under that SUPI key without checking whether an authentication procedure is already in progress and without generating a per-session unique identifier. 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. Each request is accepted and overwrites the previous authentication context. A valid EAP-AKA' response for an earlier challenge is then verified against the latest overwritten context, whose Kaut, XRES, and EapID no longer match the challenge. The result is a targeted authentication denial of service for that SUPI while the request flood is maintained. This issue was confirmed on github.com/free5gc/ausf v1.4.4 and current main as of June 2026. Details The vulnerable context pool is defined…

Published by the source

28 Aug 2026, 22:24 UTC

Last modified by the source

2 Sep 2026, 19:45 UTC

Source last checked

26 Oct 2026, 15:28 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-334q-h5g3-fpxv

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6326

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-334q-h5g3-fpxv

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# Patch Next advisory brief: CVE-2026-55784

Advisory: free5GC AUSF authentication contexts can be overwritten by concurrent requests for the same SUPI
IDs: CVE-2026-55784, GHSA-334q-h5g3-fpxv
Record: https://patchnext.com/advisories/cve-2026-55784 (revision 3, source checked 26 Oct 2026, 15:28 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/free5gc/ausf: affected <= 1.4.4

## Suggested inspection (read-only)
- Go github.com/free5gc/ausf: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/free5gc/ausf.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-334q-h5g3-fpxv (OSV record GHSA-334q-h5g3-fpxv lists affected ranges: Go github.com/free5gc/ausf >=0 <=1.4.4)
- Verified: https://osv.dev/vulnerability/GO-2026-6326 (OSV record GO-2026-6326 lists affected ranges: Go github.com/free5gc/ausf >=0)
- Verified: https://github.com/advisories/GHSA-334q-h5g3-fpxv (GitHub-reviewed advisory GHSA-334q-h5g3-fpxv lists affected ranges: Go github.com/free5gc/ausf >=0 <=1.4.4)

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