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[slackware-security] postfix (SSA:2023-356-01)

Posted on 23 December 2023
Slackware Security

[slackware-security] postfix (SSA:2023-356-01)

New postfix packages are available for Slackware 15.0 and -current to
fix a security issue.

Here are the details from the Slackware 15.0 ChangeLog:
patches/packages/postfix-3.6.13-i586-1_slack15.0.txz: Upgraded.
Security: this release adds support to defend against an email spoofing
attack (SMTP smuggling) on recipients at a Postfix server. Sites
concerned about SMTP smuggling attacks should enable this feature on
Internet-facing Postfix servers. For compatibility with non-standard
clients, Postfix by default excludes clients in mynetworks from this
The recommended settings are:
# Optionally disconnect remote SMTP clients that send bare newlines,
# but allow local clients with non-standard SMTP implementations
# such as netcat, fax machines, or load balancer health checks.
smtpd_forbid_bare_newline = yes
smtpd_forbid_bare_newline_exclusions = $mynetworks
The smtpd_forbid_bare_newline feature is disabled by default.
For more information, see:
(* Security fix *)

Where to find the new packages:

Thanks to the friendly folks at the OSU Open Source Lab
(http://osuosl.org) for donating FTP and rsync hosting
to the Slackware project! :-)

Also see the "Get Slack" section on http://slackware.com for
additional mirror sites near you.

Updated package for Slackware 15.0:

Updated package for Slackware x86_64 15.0:

Updated package for Slackware -current:

Updated package for Slackware x86_64 -current:

MD5 signatures:

Slackware 15.0 package:
1d5c7eec8f39a89e957abf39a1e79560 postfix-3.6.13-i586-1_slack15.0.txz

Slackware x86_64 15.0 package:
7286fabbc87a7dfdcc2b1ab4c6c2f4f5 postfix-3.6.13-x86_64-1_slack15.0.txz

Slackware -current package:
27f27ac76a52652599dc7b7d885fa4e1 n/postfix-3.8.4-i586-1.txz

Slackware x86_64 -current package:
c49061c599d2667dbea79227b8e6bb18 n/postfix-3.8.4-x86_64-1.txz

Installation instructions:

Upgrade the package as root:
# upgradepkg postfix-3.6.13-i586-1_slack15.0.txz

Restart the postfix server:
# /etc/rc.d/rc.postfix restart


Slackware Linux Security Team