# CVE-2026-40249

## Summary

- **CVE ID:** CVE-2026-40249
- **Severity:** MEDIUM
- **CVSS Score:** 6.9 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N)
- **CWE:** CWE-754, CWE-636
- **Published:** Apr 16, 2026
- **Last Modified:** Apr 18, 2026

## Description

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 (<= 4.2.1)

## References

- [CNA](https://github.com/free5gc/free5gc/security/advisories/GHSA-gx38-8h33-pmxr)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.32%
- **EPSS Percentile:** 24.9

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._