Is CVE-2026-43859 in the CISA KEV catalog?

No. CVE-2026-43859 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-43859?

CVE-2026-43859 has a CVSS v3 base score of 3.7 (LOW).

What is the EPSS score for CVE-2026-43859?

CVE-2026-43859 has an EPSS score of 0.16% (6th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-43859?

Upgrade mutt on debian unstable to 2.3.2-1 or later.

CVE & CISA-KEV Catalog

CVE-2026-43859

LOW

3.7

CVSS v3

NVD

Description

mutt before 2.3.2 sometimes uses strfcpy instead of memcpy for the IMAP auth_cram MD5 digest.

CWE-158

How to fix

Remediation Available

muttDebian

Fixed in:2.3.2-1CVE-2026-43859

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 ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

0.16%probability of exploitation in 30 days

6thpercentile

Low risk: more likely to be exploited than 6% of all known CVEs.

References

Other references1

github.com

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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 2026-05-05.