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James Mime4jApplication · Apache

CVE-2024-21742

MEDIUM · 5.3 CVSS v3.1 Published 2024-02-27
Fix available
A fix is available. Upgrade to after 0.8.9 or later.
See remediation →
62/100
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
Improper input validation allows for header injection in MIME4J library when using MIME4J DOM for composing message. This can be exploited by an attacker to add unintended headers to MIME messages.

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 · moderate confidence

Improper input validation in Apache James MIME4J library's DOM component allows attackers to inject arbitrary MIME headers by embedding CRLF sequences in input fields during message composition. This enables header injection attacks where unintended headers can be added to outgoing MIME messages.

MitigationUpgrade MIME4J to a patched version that implements proper input validation and sanitization to reject or neutralize CRLF sequences in header fields, or implement application-layer input validation before passing data to the MIME4J DOM API.

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
James Mime4jApplication
Affected:<= 0.8.9

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
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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. Identify MIME4J version
    Locate the mime4j jar file in your application classpath or build dependencies (check pom.xml, build.gradle, lib/ directory). Run 'jar -tf mime4j*.jar | head -1' or grep your dependency manager for 'org.apache.james:mime4j-core' to find the exact version number.
    Affected if The installed version is 0.8.9 or lower.
  2. Confirm DOM parser usage
    Search your codebase for imports of 'org.apache.james.mime4j.dom' packages. Look for usage of classes like org.apache.james.mime4j.dom.Message, org.apache.james.mime4j.dom.Header, or org.apache.james.mime4j.dom.Field. The DOM parser creates in-memory object models.
    Affected if Your code imports or uses org.apache.james.mime4j.dom classes.
  3. Check for header field input
    Review code paths where user-supplied data (form inputs, API parameters, database fields) flows into MIME header setters such as setSubject(), setFrom(), setTo(), setHeader(), or custom header field methods on Message objects.
    Affected if User input is directly assigned to header fields without prior sanitization.
  4. Inspect message generation output
    Examine generated MIME messages (saved eml files, SMTP capture logs, message headers in mail queue). Use a hex editor or 'xxd' to look for unexpected CRLF sequences (0x0D 0x0A) embedded within header field values, particularly before the blank line that separates headers from body.
    Affected if Raw MIME output contains header fields with embedded CRLF sequences that break header continuity.

You are affected if MIME4J version is 0.8.9 or lower AND your application uses the DOM component to build MIME messages from user-controlled header input.

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 a release after 0.8.9
Interim mitigation

Upgrade MIME4J to a patched version that implements proper input validation and sanitization to reject or neutralize CRLF sequences in header fields, or implement application-layer input validation before passing data to the MIME4J DOM API.

Recommended fix Moderate confidence

Version > 0.8.9 (check Apache James Mime4j releases for the specific fixed version)

  1. 1. Identify all Java projects that depend on org.apache.james:apache-mime4j-core library
  2. 2. Locate the dependency management file (pom.xml, build.gradle, or similar) in each project
  3. 3. Update the version of org.apache.james:apache-mime4j-core from 0.8.9 or earlier to a version greater than 0.8.9
  4. 4. Rebuild and test the application to ensure the header injection vulnerability is remediated
  5. 5. Verify no regression in MIME message parsing and creation functionality
Caveat Minor: Review any code that directly manipulates header fields, as behavior may have changed to enforce stricter validation

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

Fix this in James Mime4j Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2024-21742 in production — separate from our analysis above.

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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
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  • Version or environment caveats, and links to real fixes
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