CVE-2026-44320
A forged or arbitrary bearer token (e.g.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.24%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's NEF mounts the nnef-callback route group without inbound OAuth2/bearer-token authorization. A forged or arbitrary bearer token (e.g. Authorization: Bearer not-a-real-token) is enough to reach the SMF-callback handler -- the callback body is parsed and dispatched into NEF business logic instead of being rejected at the auth boundary. Same root cause as the other NEF SBI findings: the route group is mounted without any inbound auth middleware. NEF does not authenticate the producer NF identity before processing callback content; if an attacker can guess or obtain a valid NotifId, this missing auth boundary lets forged callbacks act on real subscription state. The route group is also reachable even when the runtime ServiceList does not declare it (it lists only nnef-pfdmanagement and nnef-oam). This vulnerability is fixed in 4.2.2.
- CVSS 3.1
- 7.3 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
- EPSS
- 0.24% probability · 15th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-306, CWE-862
- Affected
- free5gc/free5gc
- Source
- security-advisories@github.com
References
- https://github.com/free5gc/free5gc/issues/860Exploit, Issue Tracking
- https://github.com/free5gc/free5gc/security/advisories/GHSA-wqfh-gq79-j8mfExploit, Vendor Advisory
- https://github.com/free5gc/nef/pull/24Issue Tracking, Patch
- https://github.com/free5gc/free5gc/security/advisories/GHSA-wqfh-gq79-j8mfExploit, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.