CVE-2026-43964

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-04 · updated 2026-08-20
Weakness: CWE-193

Description

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.

Affected products

Postfix: before 3.8.16; from 3.9.0 before 3.9.10; from 3.10.0 before 3.10.9 — fixed in 3.10.9, 3.8.16, 3.9.10

How to fix

Upgrade to a fixed version: Postfix 3.10.9, 3.8.16, 3.9.10. Check the vendor advisory for mitigations.

References

https://www.mail-archive.com/postfix-announce@postfix.org/msg00110.html
http://www.openwall.com/lists/oss-security/2026/05/04/30
https://access.redhat.com/errata/RHSA-2026:25930
https://access.redhat.com/errata/RHSA-2026:25932
https://access.redhat.com/errata/RHSA-2026:26205
https://access.redhat.com/errata/RHSA-2026:50963
https://access.redhat.com/errata/RHSA-2026:50964
https://access.redhat.com/errata/RHSA-2026:51034
https://access.redhat.com/errata/RHSA-2026:51436
https://access.redhat.com/errata/RHSA-2026:57174
https://access.redhat.com/security/cve/CVE-2026-43964
https://bugzilla.redhat.com/show_bug.cgi?id=2466488

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