5.3

CVSS Score

3.1

-

CVSS Score

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CVE-2024-27305

CVE-2024-27305: aiosmtpd vulnerable to SMTP smuggling

Summary

aiosmtpd is vulnerable to inbound SMTP smuggling. SMTP smuggling is a novel vulnerability based on not so novel interpretation differences of the SMTP protocol. By exploiting SMTP smuggling, an attacker may send smuggle/spoof e-mails with fake sender addresses, allowing advanced phishing attacks. This issue also existed in other SMTP software like Postfix (https://www.postfix.org/smtp-smuggling.html).

Details

Detailed information on SMTP smuggling can be found in the full blog post (https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/) or on the Postfix homepage (https://www.postfix.org/smtp-smuggling.html). (and soon on the official website https://smtpsmuggling.com/)

Impact

With the right SMTP server constellation, an attacker can send spoofed e-mails to inbound/receiving aiosmtpd instances.

(GitHub Advisory)

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CVE-2024-27305

CVE-2024-27305:

5.3

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
aiosmtpd	pip	< 1.4.5	1.4.5

Technical Details

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Root Cause Analysis

The vulnerability stems from improper line ending handling in SMTP DATA command processing. The commit diff shows critical changes in smtp_DATA: replacing '\n' with '\r\n' in NEWLINE constant, modifying readuntil(b'\r\n'), and updating assertions/checks to require CRLF endings. This matches the SMTP smuggling mechanism described in advisories where non-RFC-compliant line endings enable command injection. The test_smtpsmuggling.py addition further confirms this was the attack vector. The function's pre-patch behavior failed to properly verify message termination sequences as required by RFC 5321 § 2.3.8.

Vulnerable functions

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WAF Protection Rules

WAF Rule

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Reasoning

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5.3

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Basic Information

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CVE-2024-27305: aiosmtpd vulnerable to SMTP smuggling

Summary

Details

Impact

CVE-2024-27305:

5.3

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Technical Details

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Vulnerable functions

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Reasoning

CVE-2024-27305: aiosmtpd vulnerable to SMTP smuggling

Summary

Details

Impact

Basic Information

Basic Information

5.3

5.3

Vulnerability IntelligenceMiggo AI

Root Cause Analysis

Vulnerable functions

Technical Details

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