CVE-2026-40249
CVE-2026-40249 is a medium-severity vulnerability in Free5gc with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-636.
Key facts
- Severity: Medium (CVSS 3.x base score 5.3)
- CVSS v4: 6.9
- EPSS exploit prediction: 0% (24th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-23316
- Weakness: CWE-636
- Affected product: Free5gc
- Published:
- Last modified:
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.
Frequently asked questions
- What is 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.
- How severe is CVE-2026-40249?
- CVE-2026-40249 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
- Is CVE-2026-40249 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-40249?
- CVE-2026-40249 affects Free5gc. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-40249?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2026-40249 have an EU (EUVD) identifier?
- Yes. CVE-2026-40249 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23316.
- When was CVE-2026-40249 published?
- CVE-2026-40249 was published on 2026-04-16 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:free5gc:free5gc:*:*:*:*:*:*:*:*
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