CVE-2021-31806 · cross-distro fix matrix

CVE-2021-31806: An issue was discovered in Squid before 4.15 and 5.x before 5.0.6. Due to a memory-management bug, it is vulnerable to a Denial of Service attack (against all clients using the proxy) via HTTP Range request processing.

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

Elevated exploitation risk

FIRST EPSS puts CVE-2021-31806's probability of exploitation in the next 30 days at 96% (100th percentile of all CVEs)— well above the noise floor. Prioritize it.

EPSS:96% · 30-day exploit probability100th percentile

Fix per ecosystem

Each block below is a distro release where CVE-2021-31806 has a known fix. Run the listed command on that distro to remediate.

Debian bullseye

Source: Debian Security Tracker

squid→ fixed in4.13-10urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y squid
```

Debian bookworm

Source: Debian Security Tracker

squid→ fixed in4.13-10urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y squid
```

Debian trixie

Source: Debian Security Tracker

squid→ fixed in4.13-10urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y squid
```

Alpine v3.20

Source: Alpine secdb

squid→ fixed in5.0.6-r0
```
apk update && apk add --upgrade squid
```

Alpine v3.21

Source: Alpine secdb

squid→ fixed in5.0.6-r0
```
apk update && apk add --upgrade squid
```

Alpine edge

Source: Alpine secdb

squid→ fixed in5.0.6-r0
```
apk update && apk add --upgrade squid
```

Alpine v3.18

Source: Alpine secdb

squid→ fixed in5.0.6-r0
```
apk update && apk add --upgrade squid
```

Alpine v3.19

Source: Alpine secdb

squid→ fixed in5.0.6-r0
```
apk update && apk add --upgrade squid
```

Are YOU affected by CVE-2021-31806?

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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