CVE-2024-27305

SMTP smuggling in aiosmtpd

MEDIUM
5.3
CVSS Score
Published: March 12, 2024 at 08:29 PM UTC
Updated: June 17, 2026 at 07:19 AM UTC
2 products affected across 1 vendorAiosmtpdLibs Aiosmtpd

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

aiosmtpd is a reimplementation of the Python stdlib smtpd.py based on asyncio. 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 is also existed in other SMTP software like Postfix. With the right SMTP server constellation, an attacker can send spoofed e-mails to inbound/receiving aiosmtpd instances. This issue has been addressed in version 1.4.5. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 1.4.5
Affected range stops below 1.4.5, so it looks safe — our inference, not a vendor statement
v < 1.4.5
Affected range stops below 1.4.5, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.3MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-345

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