CVE-2011-4318
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedDovecot 2.0.x before 2.0.16, when ssl or starttls is enabled and hostname is used to define the proxy destination, does not verify that the server hostname matches a domain name in the subject's Common Name (CN) of the X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via a valid certificate for a different hostname.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceDovecot 2.0.x before 2.0.16 fails to verify that the server hostname matches the Common Name (CN) in the X.509 certificate when acting as an SSL/TLS proxy with starttls or ssl enabled. This allows man-in-the-middle attackers to spoof SSL servers using a valid certificate issued for a different hostname.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data= 2.0.0= 2.0.1= 2.0.2= 2.0.3= 2.0.4= 2.0.5= 2.0.6= 2.0.7= 2.0.8= 2.0.9= 2.0.10= 2.0.11CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- M
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- None
AV:N/AC:M/Au:N/C:P/I:P/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed Dovecot versionRun 'dovecot --version' or check your package manager to determine the exact version of Dovecot installedAffected if The installed version is 2.0.0 through 2.0.11 (any version in the 2.0.x series before 2.0.16)
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Determine if Dovecot is acting as an SSL/TLS proxyReview Dovecot configuration files for proxy settings, specifically look for 'protocol imap { }' or 'protocol pop3 { }' sections with 'proxy' or 'ssl' or 'starttls' settings enabledAffected if Dovecot is configured to proxy connections using SSL/TLS (starttls or ssl options are enabled in proxy mode)
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Verify SSL/TLS proxy configuration existsExamine Dovecot configuration for directives such as 'ssl = yes', 'starttls = yes', or 'proxy' settings in the protocol sectionsAffected if SSL/TLS proxy functionality is enabled (either 'ssl' or 'starttls' is set to 'yes' or 'required' in Dovecot proxy configuration)
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Confirm proxy destination configurationCheck if hostname-based destination definitions are configured in the proxy settings, which would indicate proxy mode is actively being usedAffected if Proxy destinations are defined using hostnames rather than IP addresses, making the certificate-CN verification relevant
You are affected if Dovecot version is 2.0.0 through 2.0.11 AND the server is configured to act as an SSL/TLS proxy with starttls or ssl enabled using hostname-based destinations.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpgrade Dovecot to version 2.0.16 or later which implements proper hostname-to-certificate-CN verification. If upgrading is not feasible, disable SSL/TLS proxy functionality using hostname-based destination definitions.
- Consultation2.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-4318 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2011-4318 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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