CVE-2021-3634 · cross-distro fix matrix

CVE-2021-3634: A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared secrets during the lifetime of the session. One of them is called secret_hash and the other session_id. Initially, both of them are the same, but after key re-exchange, previous session_id is kept

Affects 8 Linux releases across 8 (distro × package) combinations.

Fix per ecosystem

Each block below is a distro release where CVE-2021-3634 has a known fix. Run the listed command on that distro to remediate.

Debian bullseye

Source: Debian Security Tracker

libssh→ fixed in0.9.5-1+deb11u1urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y libssh
```

Debian bookworm

Source: Debian Security Tracker

libssh→ fixed in0.9.6-1urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y libssh
```

Debian trixie

Source: Debian Security Tracker

libssh→ fixed in0.9.6-1urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y libssh
```

Alpine v3.20

Source: Alpine secdb

libssh→ fixed in0.9.6-r0
```
apk update && apk add --upgrade libssh
```

Alpine v3.21

Source: Alpine secdb

libssh→ fixed in0.9.6-r0
```
apk update && apk add --upgrade libssh
```

Alpine edge

Source: Alpine secdb

libssh→ fixed in0.9.6-r0
```
apk update && apk add --upgrade libssh
```

Alpine v3.18

Source: Alpine secdb

libssh→ fixed in0.9.6-r0
```
apk update && apk add --upgrade libssh
```

Alpine v3.19

Source: Alpine secdb

libssh→ fixed in0.9.6-r0
```
apk update && apk add --upgrade libssh
```

Are YOU affected by CVE-2021-3634?

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

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