CVE-2023-51766 · cross-distro fix matrix

CVE-2023-51766: Timo Longin discovered that Exim incorrectly handled certain SMTP messages

Affects 11 Linux releases across 35 (distro × package) combinations. First disclosed: 2026-06-03.

Fix per ecosystem

Each block below is a distro release where CVE-2023-51766 has a known fix. Run the listed command on that distro to remediate.

Ubuntu bionic

Source: Ubuntu USN

exim4→ fixed in4.90.1-1ubuntu1.10+esm6USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4
```
exim4-base→ fixed in4.90.1-1ubuntu1.10+esm6USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-base
```
exim4-config→ fixed in4.90.1-1ubuntu1.10+esm6USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-config
```
exim4-daemon-heavy→ fixed in4.90.1-1ubuntu1.10+esm6USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-daemon-heavy
```
exim4-daemon-light→ fixed in4.90.1-1ubuntu1.10+esm6USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-daemon-light
```
exim4-dev→ fixed in4.90.1-1ubuntu1.10+esm6USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-dev
```
eximon4→ fixed in4.90.1-1ubuntu1.10+esm6USN-8382-1
```
sudo apt-get install --only-upgrade -y eximon4
```

Ubuntu focal

Source: Ubuntu USN

exim4→ fixed in4.93-13ubuntu1.12+esm1USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4
```
exim4-base→ fixed in4.93-13ubuntu1.12+esm1USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-base
```
exim4-config→ fixed in4.93-13ubuntu1.12+esm1USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-config
```
exim4-daemon-heavy→ fixed in4.93-13ubuntu1.12+esm1USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-daemon-heavy
```
exim4-daemon-light→ fixed in4.93-13ubuntu1.12+esm1USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-daemon-light
```
exim4-dev→ fixed in4.93-13ubuntu1.12+esm1USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-dev
```
eximon4→ fixed in4.93-13ubuntu1.12+esm1USN-8382-1
```
sudo apt-get install --only-upgrade -y eximon4
```

Ubuntu trusty

Source: Ubuntu USN

exim4→ fixed in4.82-3ubuntu2.4+esm9USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4
```
exim4-base→ fixed in4.82-3ubuntu2.4+esm9USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-base
```
exim4-config→ fixed in4.82-3ubuntu2.4+esm9USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-config
```
exim4-daemon-heavy→ fixed in4.82-3ubuntu2.4+esm9USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-daemon-heavy
```
exim4-daemon-light→ fixed in4.82-3ubuntu2.4+esm9USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-daemon-light
```
exim4-dev→ fixed in4.82-3ubuntu2.4+esm9USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-dev
```
eximon4→ fixed in4.82-3ubuntu2.4+esm9USN-8382-1
```
sudo apt-get install --only-upgrade -y eximon4
```

Ubuntu xenial

Source: Ubuntu USN

exim4→ fixed in4.86.2-2ubuntu2.6+esm9USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4
```
exim4-base→ fixed in4.86.2-2ubuntu2.6+esm9USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-base
```
exim4-config→ fixed in4.86.2-2ubuntu2.6+esm9USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-config
```
exim4-daemon-heavy→ fixed in4.86.2-2ubuntu2.6+esm9USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-daemon-heavy
```
exim4-daemon-light→ fixed in4.86.2-2ubuntu2.6+esm9USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-daemon-light
```
exim4-dev→ fixed in4.86.2-2ubuntu2.6+esm9USN-8382-1
```
sudo apt-get install --only-upgrade -y exim4-dev
```
eximon4→ fixed in4.86.2-2ubuntu2.6+esm9USN-8382-1
```
sudo apt-get install --only-upgrade -y eximon4
```

Debian bullseye

Source: Debian Security Tracker

exim4→ fixed in4.94.2-7+deb11u2urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y exim4
```

Debian bookworm

Source: Debian Security Tracker

exim4→ fixed in4.96-15+deb12u4urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y exim4
```

Debian trixie

Source: Debian Security Tracker

exim4→ fixed in4.97-3urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y exim4
```

Alpine v3.20

Source: Alpine secdb

exim→ fixed in4.97.1-r0
```
apk update && apk add --upgrade exim
```

Alpine v3.21

Source: Alpine secdb

exim→ fixed in4.97.1-r0
```
apk update && apk add --upgrade exim
```

Alpine edge

Source: Alpine secdb

exim→ fixed in4.97.1-r0
```
apk update && apk add --upgrade exim
```

Alpine v3.19

Source: Alpine secdb

exim→ fixed in4.97.1-r0
```
apk update && apk add --upgrade exim
```

Are YOU affected by CVE-2023-51766?

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