CVE-2025-61921 · cross-distro fix matrix

CVE-2025-61921: It was discovered that Sinatra did not properly handle header parsing,

Affects 5 Linux releases across 9 (distro × package) combinations. First disclosed: 2026-07-29.

Fix per ecosystem

Each block below is a distro release where CVE-2025-61921 has a known fix. Run the listed command on that distro to remediate.

Ubuntu bionic

Source: Ubuntu USN

ruby-sinatra→ fixed in1.4.8-1ubuntu0.1~esm3USN-8624-1
```
sudo apt-get install --only-upgrade -y ruby-sinatra
```

Ubuntu focal

Source: Ubuntu USN

ruby-sinatra→ fixed in2.0.8.1-1ubuntu0.1~esm3USN-8624-1
```
sudo apt-get install --only-upgrade -y ruby-sinatra
```
ruby-rack-protection→ fixed in2.0.8.1-1ubuntu0.1~esm3USN-8624-1
```
sudo apt-get install --only-upgrade -y ruby-rack-protection
```
ruby-sinatra-contrib→ fixed in2.0.8.1-1ubuntu0.1~esm3USN-8624-1
```
sudo apt-get install --only-upgrade -y ruby-sinatra-contrib
```

Ubuntu jammy

Source: Ubuntu USN

ruby-sinatra→ fixed in2.0.8.1-2+deb11u1ubuntu0.1~esm1USN-8624-1
```
sudo apt-get install --only-upgrade -y ruby-sinatra
```
ruby-rack-protection→ fixed in2.0.8.1-2+deb11u1ubuntu0.1~esm1USN-8624-1
```
sudo apt-get install --only-upgrade -y ruby-rack-protection
```
ruby-sinatra-contrib→ fixed in2.0.8.1-2+deb11u1ubuntu0.1~esm1USN-8624-1
```
sudo apt-get install --only-upgrade -y ruby-sinatra-contrib
```

Ubuntu xenial

Source: Ubuntu USN

ruby-sinatra→ fixed in1.4.7-3ubuntu0.1~esm3USN-8624-1
```
sudo apt-get install --only-upgrade -y ruby-sinatra
```

Debian bookworm

Source: Debian Security Tracker

ruby-sinatra→ fixed in3.0.5-3+deb12u1urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y ruby-sinatra
```

Are YOU affected by CVE-2025-61921?

5-second check on your actual server. Reads /etc/os-release, uname -r, and the distro's package manager; matches against this same cross-source index live.

curl https://mindsparkstack.com/scan.sh | bash

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Continuous monitoring beats manual checking

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