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 products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| aio-libs | aiosmtpd | < 1.4.5 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | python-aiosmtpd | 1.4.6-1 | — |
| Debian 13 | python-aiosmtpd | 1.4.6-1 | — |
| Debian 12 | python-aiosmtpd | 1.4.3-1.1+deb12u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | python-aiosmtpd | No fix yet | — |
| Ubuntu 26.04 LTS | python-aiosmtpd | No fix yet | — |
| Ubuntu 25.10 | python-aiosmtpd | No fix yet | — |
| Ubuntu 24.04 LTS | python-aiosmtpd | No fix yet | — |
| Ubuntu 22.04 LTS | python-aiosmtpd | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | python-aiosmtpd | No fix yet | — |
| Ubuntu 18.04 LTS | python-aiosmtpd | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SUSE Package Hub 15 SP5 | python-aiosmtpd | 1.2.1-bp155.3.3.1 | openSUSE-SU-2024:0243-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python-aiosmtpd | 1.4.6-6.1 | openSUSE-SU-2026:11675-1 |
| openSUSE Leap 15.5 | python-aiosmtpd | 1.2.1-bp155.3.3.1 | openSUSE-SU-2024:0243-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | aiosmtpd | < 1.4.5 | 1.4.5 | GHSA-pr2m-px7j-xg65 |
Advisories 2
- openSUSE-SU-2026:11675-1 python313-aiosmtpd-1.4.6-6.1 on GA media SUSE / openSUSE Security Updates · Sep 3, 2026
- openSUSE-SU-2024:0243-1 Security update for python-aiosmtpd SUSE / openSUSE Security Updates · Feb 4, 2026