Is CVE-2026-4240 in the CISA KEV catalog?

No. CVE-2026-4240 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-4240?

CVE-2026-4240 has a CVSS v3 base score of 5.3 (MEDIUM).

What is the EPSS score for CVE-2026-4240?

CVE-2026-4240 has an EPSS score of 0.53% (41th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-4240?

Upgrade open5gs to 2.7.7 or later.

CVE & CISA-KEV Catalog

CVE-2026-4240

MEDIUM

5.3

CVSS v3

NVD

Description

A vulnerability was determined in Open5GS up to 2.7.6. The affected element is the function smf_gx_cca_cb/smf_gy_cca_cb/smf_s6b_aaa_cb/smf_s6b_sta_cb of the component CCA Handler. This manipulation causes denial of service. The attack can be initiated remotely. The exploit has been publicly disclosed and may be utilized. Upgrading to version 2.7.7 is sufficient to fix this issue. Patch name: 80eb484a6ab32968e755e628b70d1a9c64f012ec. Upgrading the affected component is recommended.

CWE-404

How to fix

Remediation Available

open5gsNVD

Affected:< 2.7.7Fixed in:2.7.7CVE-2026-4240derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityLow

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Exploit Intelligence

0.53%probability of exploitation in 30 days

41stpercentile

Moderate risk: more likely to be exploited than 41% of all known CVEs.

References

Patch1

github.com

Exploit2

Third-Party Advisory2

Release Notes1

github.com

VDB Entry1

vuldb.com

Product1

github.com

Related Vulnerabilities

Other CWE-404 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2022-44267	Medium	6.5	77%	-	Fix
CVE-2018-8120	High	7.0	74%	KEV + Ransom	-
CVE-2018-8210	High	7.8	25%	-	-
CVE-2018-8639	High	7.8	22%	KEV + Ransom	-
CVE-2023-3206	Medium	5.3	19%	-	-
CVE-2018-8450	High	8.8	16%	-	-

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-20.