Description
The SMTP server in Postfix before 2.5.13, 2.6.x before 2.6.10, 2.7.x before 2.7.4, and 2.8.x before 2.8.3, when certain Cyrus SASL authentication methods are enabled, does not create a new server handle after client authentication fails, which allows remote attackers to cause a denial of service (heap memory corruption and daemon crash) or possibly execute arbitrary code via an invalid AUTH command with one method followed by an AUTH command with a different method.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | postfix | 2.8.3-1 | — |
| Debian 13 | postfix | 2.8.3-1 | — |
| Debian 12 | postfix | 2.8.3-1 | — |
| Debian 6.0 | postfix | 2.7.1-1+squeeze1 | DSA-2233-1 |
| Debian 5.0 | postfix | 2.5.5-1.1+lenny1 | DSA-2233-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 6 | postfix +1 | 2:2.6.6-2.2.el6_1 | RHSA-2011:0843 |
| RHEL 5 | postfix +1 | 2:2.3.3-2.3.el5_6 | RHSA-2011:0843 |
| RHEL 4 | postfix +1 | 2:2.2.10-1.5.el4 | RHSA-2011:0843 |
Advisories 2
- RHSA-2011:0843 Red Hat Security Advisory: postfix security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- DSA-2233-1 postfix - several Debian Security (DSA / DLA) · Mar 9, 2026
References
- 20110509 Memory corruption in Postfix SMTP server Cyrus SASL support (CVE-2011-1720) mailing-list
- http://www.postfix.org/CVE-2011-1720.html
- 44500 third-party-advisory
- 47778 vdb-entry
- GLSA-201206-33 vendor-advisory
- 72259 vdb-entry
- VU#727230 third-party-advisory
- 1025521 vdb-entry
- [postfix-announce] 20110509 Memory corruption in Postfix SMTP server Cyrus SASL support (CVE-2011-1720) mailing-list
- http://www.postfix.org/announcements/postfix-2.8.3.html
- 8247 third-party-advisory
- SUSE-SA:2011:023 vendor-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=699035
- MDVSA-2011:090 vendor-advisory
- http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10705
- DSA-2233 vendor-advisory
- USN-1131-1 vendor-advisory
- postfix-cyrus-sasl-code-exec(67359) vdb-entry