Vulnerability in Free5gc
CVE-2026-40249
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (30.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 30th percentile — 30.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001
Affected products
- Free5gc — versions <= 4.2.1
Weakness classification (CWE)
References
- github.com/free5gc/free5gc/security/advisories/GHSA-gx38-8h33-pmxr (Exploit, Third Party Advisory, Mitigation)
Frequently asked questions
- What is CVE-2026-40249?
- CVE-2026-40249 is a medium-severity vulnerability in Free5gc, classified under CWE-636. CVSS score: 5.3/10. Published 2026-04-16.
- How severe is CVE-2026-40249?
- Medium severity. CVSS v3 base score is 5.3 out of 10.