CVE-2026-44320

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 v3.1 Score

7.3

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Weakness Type (CWE)

CWE-306 Missing Authentication

CWE-862 Missing Authorization

References

Other References

https://github.com/free5gc/free5gc/issues/860 https://github.com/free5gc/free5gc/security/advisories/GHSA-wqfh-gq79-j8mf https://github.com/free5gc/nef/pull/24 https://github.com/free5gc/free5gc/security/advisories/GHSA-wqfh-gq79-j8mf

Frequently Asked Questions

What is CVE-2026-44320? +

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. It has a CVSS v3.1 base score of 7.3 (HIGH).

How severe is CVE-2026-44320? +

CVE-2026-44320 has a CVSS v3.1 score of 7.3 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

How do I check if I'm vulnerable to CVE-2026-44320? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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