dbcve.org
Resource Allocation Without LimitsWeakness · CWE-770

CVE-2024-23184

MEDIUM · 5.0 CVSS v3.1 Published 2024-09-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
56/100
Remediation priority · Elevated
Remotely reachable 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
Having a large number of address headers (From, To, Cc, Bcc, etc.) becomes excessively CPU intensive. With 100k header lines CPU usage is already 12 seconds, and in a production environment we observed 500k header lines taking 18 minutes to parse. Since this can be triggered by external actors sending emails to a victim, this is a security issue. An external attacker can send specially crafted messages that consume target system resources and cause outage. One can implement restrictions on address headers on MTA component preceding Dovecot. 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 Dovecot's email header parsing where specially crafted messages containing an excessive number of address headers (From, To, Cc, Bcc, etc.) cause disproportionate CPU consumption. Processing 500k header lines can take 18 minutes, allowing external attackers to exhaust server resources and cause outages.

MitigationImplement header count and size restrictions on the MTA (Mail Transfer Agent) layer preceding Dovecot to reject or truncate messages with abnormally high header counts before they reach the Dovecot parser.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

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
Low
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/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 checks

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

  1. Confirm Dovecot installation and version
    Run 'dovecot --version' or check package manager (rpm -q dovecot, dpkg -l dovecot)
    Affected if Version falls within the affected range (verify against Dovecot security advisories for CVE-2024-23184)
  2. Identify Dovecot service components in use
    Check if LDA (dovecot-lda) or LMTP (dovecot-lmtp) is configured by reviewing dovecot.conf and looking for protocol lda or lmtp in the mail_plugins setting
    Affected if LDA or LMTP delivery agent is enabled and processing incoming mail
  3. Review header parsing configuration
    Examine dovecot.conf for header-related settings: grep -i 'header' /etc/dovecot/dovecot.conf; also check for mail_plugins that handle header processing
    Affected if No header count or size limits are configured in dovecot or in the mail delivery workflow
  4. Check for inbound MTA header filtering
    Inspect upstream MTA (Postfix, Exim, etc.) configuration for header_checks, header_size_limits, or mime_header_checks settings
    Affected if No header count restrictions exist at the MTA layer before Dovecot processing
  5. Analyze logs for symptoms of exploitation
    Review mail logs (mail.log, maillog) for patterns indicating processing of messages with excessive headers: look for entries with unusually long header processing times or messages with thousands of address headers
    Affected if Log entries show messages with extremely high header counts causing slow processing or service degradation

A system is affected if it runs a vulnerable Dovecot version with LDA/LMTP enabled and lacks header count restrictions at either the Dovecot or MTA layer, allowing uncontrolled header parsing to cause CPU exhaustion.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement header count and size restrictions on the MTA (Mail Transfer Agent) layer preceding Dovecot to reject or truncate messages with abnormally high header counts before they reach the Dovecot parser.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2024-23184 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2024-23184 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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