Description
Puppet 2.6.x before 2.6.12 and 2.7.x before 2.7.6, and Puppet Enterprise (PE) Users 1.0, 1.1, and 1.2 before 1.2.4, when signing an agent certificate, adds the Puppet master's certdnsnames values to the X.509 Subject Alternative Name field of the certificate, which allows remote attackers to spoof a Puppet master via a man-in-the-middle (MITM) attack against an agent that uses an alternate DNS name for the master, aka "AltNames Vulnerability."
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 11 | puppet | 2.7.6-1 | — |
| Debian 6.0 | puppet | 2.6.2-5+squeeze3 | DSA-2352-1 |
| Debian 5.0 | puppet | 0.24.5-3+lenny2 | DSA-2352-1 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
GitHub 1 repository
-
puppetlabs-toy-chest/puppetlabs-cve20113872 ★ 5 · Oct 17, 2011
Puppet Module to help fix and migrate a Puppet deployment (CVE-2011-3872)
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 1
- DSA-2352-1 puppet - programming error Debian Security (DSA / DLA) · Mar 9, 2026
References
- 46550 third-party-advisory
- USN-1238-2 vendor-advisory
- http://puppetlabs.com/blog/important-security-announcement-altnames-vulnerability/
- puppet-x509-spoofing(70970) vdb-entry
- 46578 third-party-advisory
- https://puppet.com/security/cve/cve-2011-3872
- 46934 third-party-advisory
- http://groups.google.com/group/puppet-announce/browse_thread/thread/e7edc3a71348f3e1
- 50356 vdb-entry
- 46964 third-party-advisory
- USN-1238-1 vendor-advisory