Buffer Over-Read in Postfix SMTP Server

Publication date: 2026-05-04

Last updated on: 2026-06-30

Assigner: MITRE

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.

CVSS Scores

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Meta Information

Published

2026-05-04

Last Modified

2026-06-30

Generated

2026-07-06

AI Q&A

2026-05-05

EPSS Evaluated

2026-07-05

NVD

CVE-2026-43964

Affected Vendors & Products

Vendor	Product	Version / Range
postfix	postfix	to 3.8.16 (exc)
postfix	postfix	From 3.10.0 (inc) to 3.10.9 (exc)
postfix	postfix	From 3.9.0 (inc) to 3.9.10 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-193	A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value.

Attack-Flow Graph

Executive Summary

This vulnerability affects certain versions of Postfix (before 3.8.16, 3.9 before 3.9.10, and 3.10 before 3.10.9). It occurs when an enhanced status code is received that lacks text after the third number, which can cause a buffer over-read and lead to the process crashing.

Impact Analysis

The vulnerability can cause the Postfix process to crash due to a buffer over-read. This results in a denial of service condition, potentially disrupting mail services.

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