CVE-2026-44320
free5GC: NEF nnef-callback route group is unauthenticated; forged callback requests are accepted into the processing path
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.
INFO
Published Date :
May 27, 2026, 5:16 p.m.
Last Modified :
May 28, 2026, 6:23 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update free5GC to version 4.2.2 or later.
- Ensure inbound authorization is configured for NEF routes.
- Validate producer NF identity before processing callbacks.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-44320.
| URL | Resource |
|---|---|
| https://github.com/free5gc/free5gc/issues/860 | Exploit Issue Tracking |
| https://github.com/free5gc/free5gc/security/advisories/GHSA-wqfh-gq79-j8mf | Exploit Vendor Advisory |
| https://github.com/free5gc/nef/pull/24 | Issue Tracking Patch |
| https://github.com/free5gc/free5gc/security/advisories/GHSA-wqfh-gq79-j8mf | Exploit Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-44320 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-44320
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-44320 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-44320 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
May. 28, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:free5gc:free5gc:*:*:*:*:*:*:*:* versions up to (excluding) 4.2.2 Added Reference Type GitHub, Inc.: https://github.com/free5gc/free5gc/issues/860 Types: Exploit, Issue Tracking Added Reference Type CISA-ADP: https://github.com/free5gc/free5gc/security/advisories/GHSA-wqfh-gq79-j8mf Types: Exploit, Vendor Advisory Added Reference Type GitHub, Inc.: https://github.com/free5gc/free5gc/security/advisories/GHSA-wqfh-gq79-j8mf Types: Exploit, Vendor Advisory Added Reference Type GitHub, Inc.: https://github.com/free5gc/nef/pull/24 Types: Issue Tracking, Patch -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
May. 27, 2026
Action Type Old Value New Value Added Reference https://github.com/free5gc/free5gc/security/advisories/GHSA-wqfh-gq79-j8mf -
New CVE Received by [email protected]
May. 27, 2026
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L Added CWE CWE-306 Added CWE CWE-862 Added Reference https://github.com/free5gc/free5gc/issues/860 Added Reference https://github.com/free5gc/free5gc/security/advisories/GHSA-wqfh-gq79-j8mf Added Reference https://github.com/free5gc/nef/pull/24