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Fencer Vulns
medium 5.3

CVE-2024-27305 json

SMTP smuggling in aiosmtpd

published 2024-03-12 2 y ago modified 2026-06-17 4 mo ago also GHSA-pr2m-px7j-xg65 , PYSEC-2024-221 , EUVD-2024-0215

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits
0
none known

Summary

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.

Patch / fix

  • pypi aiosmtpd 1.4.5
  • aio-libs aiosmtpd 1.4.5
  • python-aiosmtpd Debian 12 1.4.3-1.1+deb12u1
  • python-aiosmtpd Debian 14, Debian 13 1.4.6-1

debian advisories DEBIAN-CVE-2024-27305

  • python-aiosmtpd openSUSE Tumbleweed 1.4.6-6.1
  • python-aiosmtpd Package Hub 15 SP5, openSUSE Leap 15.5 1.2.1-bp155.3.3.1

opensuse advisories openSUSE-SU-2026:11675-1openSUSE-SU-2024:0243-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2024-27305 updated cvss 5.3

aio-libs/aiosmtpd: SMTP smuggling

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
OSV 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
GitHub 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
pypi aiosmtpd
<1.4.5
1.4.5

Affected products

  • aio-libs aiosmtpd

Classification

Weakness
  • CWE-345 Insufficient Verification of Data Authenticity

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.