CVE-2026-40249: FREE5GC

Medium severity, CVSS 5.3. EPSS: 0.4% chance of exploitation in the next 30 days.

free5GC is an open-source implementation of the 5G core network. In versions 4.2.1 and below of the UDR service, the PUT handler for updating Policy Data notification subscriptions at /nudr-dr/v2/policy-data/subs-to-notify/{subsId} does not return after request body retrieval or deserialization errors. Although HTTP 500 or 400 error responses are sent, execution continues and the processor is invoked with a potentially uninitialized or partially initialized PolicyDataSubscription object. This fail-open behavior may allow unintended modification of existing Policy Data notification subscriptions with invalid or empty input, depending on downstream processor and storage behavior. A patched version was not available at the time of publication.

Affected products

• FREE5GC FREE5GC: up to and including 4.2.1

Published 2026-04-16. Last modified 2026-06-17.