# CVE-2026-40249

> Vulnerability · severity: **MEDIUM** (CVSS 5.3).

## 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.

## Key facts

- **CVE ID:** CVE-2026-40249
- **Published:** 2026-04-16
- **CVSS severity:** MEDIUM
- **CVSS base score:** 5.3
- **CWE codes:** CWE-636, CWE-754

## Affected products

- `free5gc:free5gc`

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40249

## Citation

> AI Analytics. CVE-2026-40249. Retrieved 2026-07-11 from https://api.ai-analytics.org/cve/CVE-2026-40249. Derived from NIST NVD. Licensed CC0.

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