What is CVE-2026-43964?

CVE-2026-43964 is a low-severity vulnerability in Postfix, classified under Off-by-one Error. CVSS score: 3.7/10. Published 2026-05-04.

How severe is CVE-2026-43964?

Low severity. CVSS v3 base score is 3.7 out of 10.

Vulnerability in Postfix

CVE-2026-43964

Postfix before 3.8.16, 3.9 before 3.9.10, and 3.10 before 3.10.9 sometimes allows a buffer over-read and process crash via an enhanced status code that lacks text after the third number.

EPSS: 0.001 (21.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 3.7 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L.

Affected products

Postfix — versions 2.3, 3.9, 3.10

Weakness classification (CWE)

CWE-193 — Off-by-one Error

References

cve@mitre.org (Mailing List, Third Party Advisory)
af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2026-43964?: CVE-2026-43964 is a low-severity vulnerability in Postfix, classified under Off-by-one Error. CVSS score: 3.7/10. Published 2026-05-04.
How severe is CVE-2026-43964?: Low severity. CVSS v3 base score is 3.7 out of 10.