Out-of-bounds read in Postfix - CVE-2026-43964

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Main Vulnerability Database Vulnerabilities #VU131864

Out-of-bounds read in Postfix - CVE-2026-43964

Published: May 19, 2026


Vulnerability identifier: #VU131864
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-43964
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to an out-of-bounds read in Postfix status code processing when handling enhanced status codes that are not followed by additional text. A remote attacker can supply a specially crafted response or input to cause a denial of service.

This is confirmed with an access(5) table and with a DNSBL server TXT response when Postfix is configured with "$rbl_code $rbl_text" in rbl_reply_maps or default_rbl_reply, and is likely reachable through a policy server response.


Affected software

Postfix
SUSE Linux Enterprise Server 12 SP5 LTSS Extended
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Desktop 15
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for ARM 64
Anolis OS
Red Hat Enterprise Linux Server - AUS
Red Hat Enterprise Linux Server - TUS
Red Hat Enterprise Linux for x86_64 - Extended Update Support
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support
Red Hat Enterprise Linux for Power, little endian - Extended Update Support
Red Hat Enterprise Linux for ARM 64 - Extended Update Support
Ubuntu
Server Applications Module
Legacy Module
Basesystem Module
openSUSE Leap
openEuler
Fedora
Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions
postfix (Ubuntu package)
postfix-mysql-debuginfo
postfix-doc
postfix-mysql
postfix-devel
postfix-debuginfo
postfix-debugsource
postfix
postfix-sysvinit
postfix-help
postfix-pgsql
postfix-perl-scripts
postfix-cdb
postfix (Red Hat package)
postfix-ldap
postfix-pcre
postfix-sqlite
postfix-bdb-debuginfo
postfix-bdb-lmdb-debuginfo
postfix-postgresql-debuginfo
postfix-postgresql
postfix-bdb
postfix-ldap-debuginfo
postfix-bdb-debugsource
postfix-bdb-lmdb
postfix-lmdb

How to mitigate CVE-2026-43964

Install security update from vendor's website.

Postfix - addressed in versions 3.8.17, 3.9.11, 3.10.10, 3.11.3
postfix (Ubuntu package) - addressed in versions 2.11.0-1ubuntu1.2+esm4, 3.1.0-3ubuntu0.4+esm4, 3.3.0-1ubuntu0.4+esm4, 3.4.13-0ubuntu1.4+esm1, 3.6.4-1ubuntu1.4, 3.8.6-1ubuntu0.1, 3.10.2-1ubuntu2.1, 3.10.6-4ubuntu2.1
postfix-mysql-debuginfo - addressed in versions 3.2.10-3.33.1, 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix-doc - addressed in versions 3.2.10-3.33.1, 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix-mysql - addressed in versions 3.2.10-3.33.1, 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix-devel - addressed in versions 3.2.10-3.33.1, 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix-debuginfo - addressed in versions 3.2.10-3.33.1, 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix-debugsource - addressed in versions 3.2.10-3.33.1, 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix - addressed in versions 3.2.10-3.33.1, 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix-sysvinit - addressed in versions 3.3.1-16, 3.3.1-22, 3.8.4-2
postfix-help - addressed in versions 3.3.1-16, 3.3.1-22, 3.8.4-2
postfix-pgsql - addressed in versions 3.3.1-16, 3.3.1-22, 3.8.4-2
postfix-perl-scripts - addressed in versions 3.3.1-16, 3.3.1-22, 3.8.4-2
postfix-debugsource - addressed in versions 3.3.1-16, 3.3.1-22, 3.8.4-2
postfix-debuginfo - addressed in versions 3.3.1-16, 3.3.1-22, 3.8.4-2
postfix - addressed in versions 3.3.1-16, 3.3.1-22, 3.8.4-2
postfix-cdb - update to 3.3.1-16
postfix (Red Hat package) - addressed in versions 3.5.8-1.el8_4.1, 3.5.8-4.el8_6.1, 3.5.8-4.el8_8.1, 3.5.8-8.el8_10, 3.8.5-8.el10_0.1, 3.8.5-10.el10_2
postfix-mysql - addressed in versions 3.5.8-8.0.2, 3.8.5-2
postfix - addressed in versions 3.5.8-8.0.2, 3.8.5-2
postfix-cdb - addressed in versions 3.5.8-8.0.2, 3.8.5-2
postfix-ldap - addressed in versions 3.5.8-8.0.2, 3.8.5-2
postfix-pcre - addressed in versions 3.5.8-8.0.2, 3.8.5-2
postfix-perl-scripts - addressed in versions 3.5.8-8.0.2, 3.8.5-2
postfix-pgsql - addressed in versions 3.5.8-8.0.2, 3.8.5-2
postfix-sqlite - addressed in versions 3.5.8-8.0.2, 3.8.5-2
postfix-bdb-debuginfo - addressed in versions 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix-bdb-lmdb-debuginfo - addressed in versions 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix-postgresql-debuginfo - addressed in versions 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix-postgresql - addressed in versions 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix-ldap - addressed in versions 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix-bdb - addressed in versions 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix-ldap-debuginfo - addressed in versions 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix-bdb-debugsource - addressed in versions 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix-bdb-lmdb - addressed in versions 3.5.9-150300.5.20.1, 3.8.4-150600.3.6.1
postfix-lmdb - update to 3.8.5-2
postfix - addressed in versions 3.9.11-1.fc42, 3.10.10-1.fc43, 3.10.10-1.fc44

External References

Related Security Bulletins