Description
socket.c in fetchmail before 6.3.11 does not properly handle a '\0' character in a domain name in the subject's Common Name (CN) field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority, a related issue to CVE-2009-2408.
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 | fetchmail | 6.3.9~rc2-6 | — |
| Debian 13 | fetchmail | 6.3.9~rc2-6 | — |
| Debian 12 | fetchmail | 6.3.9~rc2-6 | — |
| Debian 5.0 | fetchmail | 6.3.9~rc2-4+lenny1 | DSA-1852-1 |
| Debian 4.0 | fetchmail | 6.3.6-1etch2 | DSA-1852-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 5 | fetchmail | 6.3.6-1.1.el5_3.1 | RHSA-2009:1427 |
| RHEL 4 | fetchmail | 6.2.5-6.0.1.el4_8.1 | RHSA-2009:1427 |
| RHEL 3 | fetchmail | 6.2.0-3.el3.5 | RHSA-2009:1427 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | fetchmail | 6.3.26-13.4 | openSUSE-SU-2024:10194-1 |
Advisories 3
- RHSA-2009:1427 Red Hat Security Advisory: fetchmail security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- DSA-1852-1 fetchmail - SSL certificate verification weakness Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:10194-1 fetchmail-6.3.26-13.4 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- MDVSA-2009:201 vendor-advisory
- 36175 third-party-advisory
- 36236 third-party-advisory
- DSA-1852 vendor-advisory
- http://fetchmail.berlios.de/fetchmail-SA-2009-01.txt
- [oss-security] 20090805 Re: CVE request: fetchmail <= 6.3.10 SSL certificate mailing-list
- 20090806 fetchmail security announcement fetchmail-SA-2009-01 (CVE-2009-2666) mailing-list
- SSA:2009-218-01 vendor-advisory
- 36179 third-party-advisory
- 1022679 vdb-entry
- 56855 vdb-entry
- oval:org.mitre.oval:def:11059 vdb-entry signature
- ADV-2009-3184 vdb-entry
- ADV-2009-2155 vdb-entry
- APPLE-SA-2009-11-09-1 vendor-advisory
- http://support.apple.com/kb/HT3937
- 35951 vdb-entry