CVE-2026-40343: free5GC UDR: Fail-open handling in PolicyDataSubsToNotifyPost allows unintended subscription creation

Vulnerability summary

CVE-2026-40343 is a medium (CVSS 6.9) vulnerability in free5gc. EPSS estimates a 0.31% chance of exploitation in the next 30 days, higher than 22.6% of scored vulnerabilities.

Timeline

1. 21-04-2026
   PublishedVulnerability first disclosed.
2. 22-04-2026
   Last modifiedVulnerability information updated.

Description

free5GC UDR is the user data repository (UDR) for free5GC, an an open-source project for 5th generation (5G) mobile core networks. In versions up to and including 1.4.2, a fail-open request handling flaw in the UDR service causes the `/nudr-dr/v2/policy-data/subs-to-notify` POST handler to continue processing requests even after request body retrieval or deserialization errors. This may allow unintended creation of Policy Data notification subscriptions with invalid, empty, or partially processed input, depending on downstream processor behavior. As of time of publication, a patched version is not available.

• CWE-754Improper Check for Unusual or Exceptional ConditionsThe product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.