Description
The STARTTLS implementation in Postfix 2.4.x before 2.4.16, 2.5.x before 2.5.12, 2.6.x before 2.6.9, and 2.7.x before 2.7.3 does not properly restrict I/O buffering, which allows man-in-the-middle attackers to insert commands into encrypted SMTP sessions by sending a cleartext command that is processed after TLS is in place, related to a "plaintext command injection" attack.
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 | 2.8.0-1 | — |
| Debian 13 | postfix | 2.8.0-1 | — |
| Debian 12 | postfix | 2.8.0-1 | — |
| 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 | 2:2.6.6-2.1.el6_0 | RHSA-2011:0423 |
| RHEL 5 | postfix +1 | 2:2.3.3-2.2.el5_6 | RHSA-2011:0422 |
| RHEL 4 | postfix +1 | 2:2.2.10-1.4.el4 | RHSA-2011:0422 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | pure-ftpd | 1.0.43-1.3 | openSUSE-SU-2024:10318-1 |
Advisories 4
- RHSA-2011:0423 Red Hat Security Advisory: postfix security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- RHSA-2011:0422 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
- openSUSE-SU-2024:10318-1 pure-ftpd-1.0.43-1.3 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- http://www.oracle.com/technetwork/topics/security/cpuapr2011-301950.html
- multiple-starttls-command-execution(65932) vdb-entry
- http://www.postfix.org/CVE-2011-0411.html
- 43646 third-party-advisory
- SUSE-SR:2011:009 vendor-advisory
- 71021 vdb-entry
- ADV-2011-0752 vdb-entry
- ADV-2011-0891 vdb-entry
- GLSA-201206-33 vendor-advisory
- FEDORA-2011-3355 vendor-advisory
- 43874 third-party-advisory
- FEDORA-2011-3394 vendor-advisory
- http://www.kb.cert.org/vuls/id/MORO-8ELH6Z
- APPLE-SA-2011-10-12-3 vendor-advisory
- ADV-2011-0611 vdb-entry
- 46767 vdb-entry
- RHSA-2011:0423 vendor-advisory
- VU#555316 third-party-advisory
- 1025179 vdb-entry
- RHSA-2011:0422 vendor-advisory
- http://support.apple.com/kb/HT5002
- http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10705
- DSA-2233 vendor-advisory
- [oss-security] 20210810 STARTTLS vulnerabilities mailing-list