# CVE-2026-94043: Free5GC race condition in GMM handler RanUe context access

Source: https://junglewise.ai/threats/cve-2026-94043-a-vulnerability-was-determined-in-free5gc-up-to-4-2-3-this  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-20. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-94043 · Severity: medium · CVSS 5.3 · Published 2026-09-20

Free5GC is an open-source implementation of a 5G core network. A race condition in the AMF (Access and Mobility Management Function) component allows an attacker to exploit concurrent access to RanUe context data, potentially causing service disruption or data inconsistency in 5G authentication and mobility management. The vulnerability is triggered by network-based access without requiring authentication.

Technologies: [free5GC](https://junglewise.ai/threats/technologies/free5gc). Vendors: [free5GC](https://junglewise.ai/threats/vendors/free5gc).

## Quick answers

**Is CVE-2026-94043 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-94043 being exploited in the wild.

**How severe is CVE-2026-94043?** Medium severity, with a CVSS score of 5.3, published 20 September 2026.

**Which products and versions are affected?** free5GC up to 4.2.3.

**Is there a fix for CVE-2026-94043?** A patch was published on 2026-08-27: Commit e323b01 merged Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-94043 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-94043?** Check whether you run free5GC at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is a race condition in the GMM handler's RanUe context management within Free5GC's AMF component. The RanUe map was accessed without proper synchronization (mutex protection), allowing concurrent read/write operations to corrupt shared state. The fix adds a sync.RWMutex (ranUeMu) to serialize access to the RanUe context map, eliminating the data race.

## Affected products

- Free5GC Free5GC up to 4.2.3

## Timeline

- 2026-09-20: disclosed
- 2026-08-27: patched: Commit e323b01 merged

## References

- [https://github.com/free5gc/amf/commit/e323b01464355781b8b8d5dd695e05cbc00a62f2](https://github.com/free5gc/amf/commit/e323b01464355781b8b8d5dd695e05cbc00a62f2)
- [https://github.com/free5gc/amf/pull/238](https://github.com/free5gc/amf/pull/238)

## Related threats

- [Free5GC SMF resource exhaustion in PFCP session establishment](https://junglewise.ai/threats/cve-2026-106805-a-resource-exhaustion-issue-exists-in-free5gc-v4-2-3-during-pfcp)
- [Free5GC UPF nil pointer dereference in PFCP Session Report](https://junglewise.ai/threats/cve-2026-75439-free5gc-upf-nil-pointer-dereference-in-pfcp-session-report)
- [free5GC NRF input validation bypass in NF profile registration](https://junglewise.ai/threats/cve-2026-55068-free5gc-nrf-input-validation-bypass-in-nf-profile-registration)
- [free5gc NSSF nil pointer dereference in NssaiAvailabilitySubscriptionCreate](https://junglewise.ai/threats/cve-2026-30073-free5gc-nssf-nil-pointer-dereference-in)
- [free5gc RechargePut denial of service in input parsing](https://junglewise.ai/threats/cve-2026-30071-free5gc-rechargeput-denial-of-service-in-input-parsing)