CVE-2021-20230 · cross-distro fix matrix

CVE-2021-20230: A flaw was found in stunnel before 5.57, where it improperly validates client certificates when it is configured to use both redirect and verifyChain options. This flaw allows an attacker with a certificate signed by a Certificate Authority, which is not the one accepted by the stunnel server, to ac

Affects 3 Linux releases across 3 (distro × package) combinations.

Fix per ecosystem

Each block below is a distro release where CVE-2021-20230 has a known fix. Run the listed command on that distro to remediate.

Debian bullseye

Source: Debian Security Tracker

stunnel4→ fixed in3:5.56+dfsg-8urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y stunnel4
```

Debian bookworm

Source: Debian Security Tracker

stunnel4→ fixed in3:5.56+dfsg-8urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y stunnel4
```

Debian trixie

Source: Debian Security Tracker

stunnel4→ fixed in3:5.56+dfsg-8urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y stunnel4
```

Are YOU affected by CVE-2021-20230?

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

Form-based quickscan View on NVD

Continuous monitoring beats manual checking

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