GHSA-vrrx-58h3-prmh — amf
LOWGHSA-vrrx-58h3-prmh is a low-severity (CVSS 3.7) CWE-358 vulnerability in github.com/free5gc/amf. No vendor fix is recorded yet; mitigation options are listed below.
Free5GC AMF has Missing Concurrent NAS SMC Validation During NGAP Handover
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-vrrx-58h3-prmh.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-vrrx-58h3-prmh plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/free5gc/amfReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
The AMF in Free5GC v4.2.1 does not enforce the concurrent security procedure rules defined in 3GPP TS 33.501 §6.9.5.1. The AMF does not check for ongoing N2 handover procedures before initiating a NAS Security Mode Command, and vice versa. This can lead to mismatches between NAS and AS security contexts in the network and the UE.
Details
Vulnerability Type: CWE-358 (Improperly Implemented Security Check for Standard)
Affected File: internal/ngap/handler.go — handleHandoverRequiredMain() and internal/gmm/sm.go — SecurityMode()
Root Cause:
3GPP TS 33.501 §6.9.5.1 states:
"Concurrent runs of security procedures may, in certain situations, lead to mismatches between security contexts in the network and the UE. In order to avoid such mismatches, the following rules shall be adhered to:
- AMF shall not initiate any of the N2 procedures including a new key towards a UE if a NAS Security Mode Command procedure is ongoing with the UE.
- The AMF shall not initiate a NAS Security Mode Command towards a UE if one of the N2 procedures including a new key is ongoing with the UE."
Free5GC AMF uses an OnGoing state tracking mechanism (SetOnGoing(), GetOnGoing()) with OnGoingProcedureN2Handover type. However, the cross-procedure checks required by §6.9.5.1 are not implemented:
Rule 2 violation:
SecurityMode() in internal/gmm/sm.go sends SMC on EntryEvent without checking if N2 handover is ongoing.
Rule 1 violation:
handleHandoverRequiredMain() in internal/ngap/handler.go calls SetOnGoing(OnGoingProcedureN2Handover) without checking if SMC is ongoing.
Why NH/NCC and SMC are related:
SMC activates a new KAMF, which changes the basis for NH key derivation. The N2 HandoverRequest includes NH/NCC derived from the old KAMF. If both procedures run concurrently, the target gNB and UE derive different KgNB keys, breaking AS security.
PoC
Source code evidence:
Free5GC AMF internal/gmm/sm.go — SecurityMode():
func SecurityMode(state *fsm.State, event fsm.EventType, args fsm.ArgsType) {
switch event {
case fsm.EntryEvent:
// No check for OnGoing N2 procedure
// Directly proceeds to SMC
Free5GC AMF internal/ngap/handler.go — handleHandoverRequiredMain():
amfUe.SetOnGoing(sourceUe.Ran.AnType, &context.OnGoing{
Procedure: context.OnGoingProcedureN2Handover,
})
// No check for ongoing SMC before setting N2
Packet Evidence (pcap available):
| Packet | Time | Message | Description |
|---|---|---|---|
| #1 | 0.000s | HandoverRequired | gNB_A requests handover |
| #18 | 0.002s | HandoverRequest | N2 started (NH/NCC included) |
| (no response from gNB_B) | N2 ongoing | ||
| #28 | 2.062s | Registration request | UE re-registers (same SUPI) |
| #63 | 2.069s | Authentication request | |
| #64 | 2.070s | Authentication response | |
| #71 | 2.072s | Security mode command | SMC during N2 ongoing = Rule 2 violation |
| NGAPHandover-N2-SMC-Concurrent.zip |
Impact
Integrity (MEDIUM): Concurrent NAS and AS security procedures can cause security context mismatches between UE, AMF, and gNB. The SMC activates a new KAMF while the N2 HandoverRequest carries NH/NCC derived from the old KAMF, resulting in KgNB derivation mismatch.
Availability (LOW): Security context mismatch may cause handover failure or security verification failures.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/free5gc/amf | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/free5gc/amf, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of github.com/free5gc/amf has shipped for GHSA-vrrx-58h3-prmh yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-vrrx-58h3-prmh can be triaged on real exposure rather than presence alone.
Tailored to GHSA-vrrx-58h3-prmh. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-vrrx-58h3-prmh in your dependencies?
O3 Security finds GHSA-vrrx-58h3-prmh across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.