Free5GC up to 1.4.2 UDR Service improper authorization

Summaryinfo

A vulnerability marked as critical has been reported in Free5GC up to 1.4.2. This issue affects some unknown processing of the component UDR Service. The manipulation leads to improper authorization. This vulnerability is uniquely identified as CVE-2026-40247. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Free5GC up to 1.4.2. This issue affects an unknown code of the component UDR Service. The manipulation with an unknown input leads to a improper authorization vulnerability. Using CWE to declare the problem leads to CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. Impacted is confidentiality. The summary by CVE is:

free5GC is an open-source implementation of the 5G core network. In versions 4.2.1 and below of the UDR service, the handler for reading Traffic Influence Subscriptions checks whether the influenceId path segment equals subs-to-notify, but does not return after sending the HTTP 404 response when validation fails. Execution continues and the subscription data is returned alongside the 404 response. An unauthenticated attacker with access to the 5G Service Based Interface can read arbitrary Traffic Influence Subscriptions, including SUPIs/IMSIs, DNNs, S-NSSAIs, and callback URIs, by supplying any value for the influenceId path segment. A patched version was not available at the time of publication.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-40247 since 04/10/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 04/17/2026). MITRE ATT&CK project uses the attack technique T1548.002 for this issue.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

• Free5GC

Version

• 1.4.0
• 1.4.1
• 1.4.2

Website

• Product: https://github.com/free5gc/free5gc/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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