Is CVE-2023-40440 in the CISA KEV catalog?

No. CVE-2023-40440 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2023-40440?

CVE-2023-40440 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2023-40440?

CVE-2023-40440 has an EPSS score of 0.45% (36th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2023-40440?

Upgrade macos to 12.6.8 or later.

CVE & CISA-KEV Catalog

CVE-2023-40440

HIGH

7.5

CVSS v3

NVD

Description

This issue was addressed with improved state management of S/MIME encrypted emails. This issue is fixed in macOS Monterey 12.6.8. A S/MIME encrypted email may be inadvertently sent unencrypted.

How to fix

Remediation Available

macosNVD

Affected:>= 12.0.0, < 12.6.8Fixed in:12.6.8CVE-2023-40440derived 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

ConfidentialityHigh

IntegrityNone

AvailabilityNone

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

Exploit Intelligence

0.45%probability of exploitation in 30 days

36thpercentile

Low risk: more likely to be exploited than 36% of all known CVEs.

References

Vendor Advisory1

support.apple.com

Other references1

blog.aegrel.ee

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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 2025-06-25.