dbcve.org
FedoraOperating system · Fedoraproject

CVE-2015-3420

MEDIUM · 5.9 CVSS v3.0 Published 2017-09-19
Fix available
A fix is available. Upgrade to after 2.2.16 or later.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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 · unedited
The ssl-proxy-openssl.c function in Dovecot before 2.2.17, when SSLv3 is disabled, allow remote attackers to cause a denial of service (login process crash) via vectors related to handshake failures.

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 confidence

In Dovecot before 2.2.17, the ssl-proxy-openssl.c function contains a flaw where SSL handshake failures cause a crash in the login process when SSLv3 is disabled, resulting in a denial of service.

MitigationUpdate Dovecot to version 2.2.17 or later to obtain the fix for this vulnerability.

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
FedoraOperating system
Affected:= 20= 21= 22
DovecotApplication
Affected:<= 2.2.16

CVSS 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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

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 checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Dovecot version
    Run 'dovecot --version' or 'rpm -q dovecot' to obtain the installed version number
    Affected if Version is 2.2.16 or lower
  2. Verify SSL support is enabled
    Inspect Dovecot configuration files (typically /etc/dovecot/dovecot.conf and /etc/dovecot/conf.d/) for ssl settings. Look for 'ssl = yes' or 'ssl_cert' and 'ssl_key' directives
    Affected if SSL is enabled and configured with certificates
  3. Check SSL protocol configuration
    Look for ssl_protocols setting in Dovecot SSL configuration files (commonly in 10-ssl.conf or similar). Run 'doveconf -a' to see all active settings
    Affected if SSLv3 is explicitly disabled or not included in allowed protocols, triggering the crash condition on handshake failure
  4. Confirm login process uses SSL proxy
    Verify that the login process uses ssl-proxy-openssl.c by checking if imap-login or pop3-login processes handle SSL connections. Review dovecot configuration for 'login_ssl' or 'ssl' in login processes
    Affected if Login processes handle SSL connections through the ssl-proxy-openssl module

The environment is affected if Dovecot version is 2.2.16 or lower, SSL is enabled with SSLv3 disabled, and SSL handshake failures in the login process can trigger a crash.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Upgrade available Upgrade to a release after 2.2.16
Interim mitigation

Update Dovecot to version 2.2.17 or later to obtain the fix for this vulnerability.

Fix this in Fedora Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
4.0 hours of engineering $750
Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2015-3420 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data