CVE-2023-51747Public exploitNetwork attack vector

Email forgery via lenient DATA delimiter parsing

Published Feb 27, 2024 · Updated Feb 13, 2025

SMTP smuggling in Apache James Server 3.7.4 and earlier and 3.8.0 allows attackers to forge email envelopes across SMTP relays. DataLineJamesMessageHookHandler accepts DATA lines lacking the required CRLF terminator, so downstream servers can parse embedded text as a second SMTP envelope. Exploitation requires a second SMTP server with a conflicting end-of-data interpretation; a successful chain bypasses SPF and delivers forged mail.

CVSS severity7.1
High
EPSS probability1.04%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SMTP smuggling in Apache James Server 3.7.4 and earlier and 3.8.0 allows attackers to forge email envelopes across SMTP relays. DataLineJamesMessageHookHandler accepts DATA lines lacking the required CRLF terminator, so downstream servers can parse embedded text as a second SMTP envelope. Exploitation requires a second SMTP server with a conflicting end-of-data interpretation; a successful chain bypasses SPF and delivers forged mail.

The record

CVE
CVE-2023-51747
Published
Feb 27, 2024
Updated
Feb 13, 2025
Vendor
The Apache Software Foundation
Product
Apache James Server
Classifications
CWE-290, CWE-20, CWE-444, T1656
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 2024CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 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 <=3.7.4
  2. Affected versionversion=3.8 <=3.8.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Apache Software Foundation · Apache James Serverversion=0 <=3.7.4; version=3.8 <=3.8.0

Published CVSS scores

7.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-290Authentication Bypass by Spoofing
CWE-20Improper Input Validation
CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1656Impersonation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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