CVE-2026-42081 free5GC: UE Security Capability bypass on NGAP PathSwitchRequest
A malicious gNB can bypass UE security capability checks in free5GC AMF, causing persistent handover denial-of-service for users.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42081?
CVE-2026-42081 is a medium-severity vulnerability in Free5gc Free5gc, published on 27 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, the AMF in Free5GC does not verify the UE Security Capabilities received in NGAP PathSwitchRequest messages against its locally stored values, as mandated by 3GPP TS 33.501 §6.7.3.1. A malicious gNB can overwrite the AMF's stored UE security capabilities with arbitrary values, which are then propagated in PathSwitchRequest Acknowledge messages and subsequent Handover Request messages. This leads to persistent handover denial-of-service for affected UEs. This vulnerability is fixed in 4.2.2.
Weakness: CWE-358
Which versions are affected by CVE-2026-42081?
3 open source packages ship an affected version, including github.com/free5gc/amf. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/free5gc/amf Go | All versions | None |
github.com/free5gc/amf Go | All versions to 1.4.3 | None |
github.com/free5gc/amf Go | All versions to 1.4.3 | None |
Products include Free5gc Free5gc.
How do I fix CVE-2026-42081?
Upgrade to a fixed version.
Is CVE-2026-42081 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42081 exists.
Other vulnerabilities in Free5gc Free5gc
- CVE-2026-44327 free5GC: NEF nnef-oam route group is unauthenticated; no-token requests reach the OAM handler
- CVE-2026-44329 free5GC's SMF UPI management interface lacks auth middleware; unauthenticated topology read/write requests reach handlers
- CVE-2026-44330 free5GC's NEF nnef-pfdmanagement API is unauthenticated; forged bearer tokens can read PFD data and create/delete PFD subscriptions
- CVE-2025-63679 Memory corruption in n/a
- CVE-2026-44315 free5GC's NEF 3gpp-pfd-management API is unauthenticated; forged bearer tokens can create, read, and delete PFD transactions
Sources
Also known as GHSA-77x9-rf64-92gv, GO-2026-5209.