Vulnerability in github.com/free5gc/ausf (CVE-2026-55784)
Summary
Vulnerability in github.com/free5gc/ausf (CVE-2026-55784). Risk of unauthorized operations or information disclosure. Exploitable via POST /nausf-auth/v1/ue-authentications.
Original description
The description as published by the source.
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 K_aut, 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 in internal/context/context.go.
UePool is a sync.Map, which makes individual map operations safe, but it does not make the authentication procedure state safe. The problem is the session design: the key is only the SUPI, and Store() unconditionally replaces any active context for that SUPI.
type AUSFContext struct {
suciSupiMap sync.Map
UePool sync.Map
// ...
}
type AusfUeContext struct {
Supi string
// ...
// for EAP-AKA'…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-55784 has been found in github.com/free5gc/ausf.
Attackers can target a specific entry point like POST /nausf-auth/v1/ue-authentications over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "github.com/free5gc/ausf CVE-2026-55784" on the vendor's site.
CVE-2026-55784 (github.com/free5gc/ausf) — CWE-362 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: POST /nausf-auth/v1/ue-authentications / POST /ue-authentications / POST /eap-session / sync.Map
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-362) exists in github.com/free5gc/ausf. Attackers reach the vulnerable code path via POST /nausf-auth/v1/ue-authentications without authentication.
Check the vendor advisory for the affected versions of github.com/free5gc/ausf. Attack surface: POST /nausf-auth/v1/ue-authentications / POST /ue-authentications / POST /eap-session / sync.Map.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual POST /nausf-auth/v1/ue-authentications requests with malformed payloads or SQL meta-characters. Run grep -r 'github.com/free5gc/ausf' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'github.com/free5gc/ausf' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
github.com/free5gc/ausfを grep し、稼働しているサービス・バージョンを把握する。 -
2Hunt for indicators of compromise detect
grep 'POST /nausf-auth/v1/ue-authentications' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /nausf-auth/v1/ue-authenticationsへの異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Post-deployment verification verify
Replay attack against POST /nausf-auth/v1/ue-authentications on staging to confirm patch closes the vectorパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
References
- package github.com
- web github.com
- web github.com