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DovecotApplication

CVE-2025-59028

HIGH · 7.5 CVSS v3.1 Published 2026-03-27
Fix available
A fix is available. Upgrade to 2.4.3 / 3.1.2 or later.
See remediation →
84/100
Remediation priority · High
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
When sending invalid base64 SASL data, login process is disconnected from the auth server, causing all active authentication sessions to fail. Invalid BASE64 data can be used to DoS a vulnerable server to break concurrent logins. Install fixed version or disable concurrency in login processes (heavy perfomance penalty on large deployments). No publicly available exploits are known.

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

A denial of service vulnerability exists in the login authentication system where sending invalid base64-encoded SASL data causes the login process to disconnect from the authentication server, resulting in all active authentication sessions failing simultaneously.

MitigationInstall the vendor-provided fixed version of the software; alternatively, disable concurrency in login processes as a workaround (noting significant performance degradation on large deployments).

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
DovecotApplication
Affected:< 2.4.3
DovecotApplication
Affected:< 3.1.2

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

CVSS:3.1/AV:N/AC:L/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. Identify Dovecot installation
    Run 'dovecot --version' to get the installed version, or check via package manager (e.g., 'rpm -q dovecot' or 'dpkg -l dovecot')
    Affected if The command fails or returns no version, indicating Dovecot may not be installed
  2. Determine if Open Xchange Dovecot variant is used
    Check installed packages for 'ox-dovecot' or 'open-xchange-dovecot' via package manager, or examine /opt directory for OX-specific paths
    Affected if Open Xchange Dovecot package is found and version cannot be determined or is below 3.1.2
  3. Compare base Dovecot version against affected range
    If standard Dovecot is installed, compare the version number to 2.4.3 (e.g., 2.4.0, 2.4.1, 2.4.2 are vulnerable; 2.4.3 and above are fixed)
    Affected if Installed version is less than 2.4.3 for the base Dovecot product
  4. Compare Open Xchange Dovecot version against affected range
    If Open Xchange Dovecot is installed, compare its version to 3.1.2 (versions below 3.1.2 are vulnerable)
    Affected if Installed version is less than 3.1.2 for the Open Xchange Dovecot variant
  5. Verify login authentication is in use
    Check dovecot configuration files (dovecot.conf, conf.d/) for 'login' service or SASL authentication settings (e.g., 'protocols = imap pop3' with auth mechanisms)
    Affected if Login service and SASL authentication are enabled - this is the vulnerable component
  6. Confirm authentication server handles base64 SASL data
    Review logs for base64-encoded SASL authentication attempts (typically logged at debug or info level) or verify auth mechanism supports PLAIN/LOGIN which use base64 encoding
    Affected if Base64-encoded SASL authentication mechanisms (PLAIN, LOGIN) are configured and active

You are affected if Dovecot or Open Xchange Dovecot is installed with a version lower than 2.4.3 or 3.1.2 respectively, and login authentication with SASL is enabled.

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.

dbcve · scoped
Upgrade available Upgrade to 2.4.3 / 3.1.2 or later
Fixed in 2.4.33.1.2
Interim mitigation

Install the vendor-provided fixed version of the software; alternatively, disable concurrency in login processes as a workaround (noting significant performance degradation on large deployments).

Recommended fix High confidence

Dovecot 2.4.3 (2.x branch) or Dovecot 3.1.2 (3.x branch)

  1. 1. Identify current Dovecot version by running 'dovecot --version'
  2. 2. For Dovecot 2.x installations: upgrade to version 2.4.3 or later
  3. 3. For Dovecot 3.x installations: upgrade to version 3.1.2 or later
  4. 4. Use your system's package manager (apt, yum, dnf) or compile from source to obtain the fixed version
  5. 5. Review Dovecot configuration for any needed adjustments after upgrade
  6. 6. Test authentication functionality in a staging environment before production deployment
  7. 7. Deploy the upgrade to production servers
  8. 8. Monitor authentication logs to verify the fix resolves the DoS vulnerability

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Dovecot Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.

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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-2025-59028 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