CVE-2024-21742Network attack vector

Message-header injection via unchecked CRLF

Published Feb 27, 2024 · Updated May 6, 2025

Header injection in Apache James Mime4J 0.8.9 and earlier allows remote attackers to add unintended headers to composed MIME messages. The RawField constructor accepts unencoded CRLF sequences in a header body, so the DOM message writer serializes attacker-controlled text as a separate header. Exploitation requires a consuming application to pass attacker-controlled header content to the DOM composition API; parsing MIME messages alone does not expose the flaw.

CVSS severity5.3
Medium
EPSS probability1.09%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Header injection in Apache James Mime4J 0.8.9 and earlier allows remote attackers to add unintended headers to composed MIME messages. The RawField constructor accepts unencoded CRLF sequences in a header body, so the DOM message writer serializes attacker-controlled text as a separate header. Exploitation requires a consuming application to pass attacker-controlled header content to the DOM composition API; parsing MIME messages alone does not expose the flaw.

The record

CVE
CVE-2024-21742
Published
Feb 27, 2024
Updated
May 6, 2025
Vendor
The Apache Software Foundation
Product
Apache James Mime4J
Classifications
CWE-74, CWE-20
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 27, 2024CVE publishedPublication date reported by the CVE source.
  2. May 6, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=0.8.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache James Mime4Jversion=0 <=0.8.9

Published CVSS scores

5.3GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
CWE-20Improper Input Validation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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