CVE-2021-3520 · cross-distro fix matrix

CVE-2021-3520: There's a flaw in lz4. An attacker who submits a crafted file to an application linked with lz4 may be able to trigger an integer overflow, leading to calling of memmove() on a negative size argument, causing an out-of-bounds write and/or a crash. The greatest impact of this flaw is to availability,

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

Fix per ecosystem

Each block below is a distro release where CVE-2021-3520 has a known fix. Run the listed command on that distro to remediate.

Debian bullseye

Source: Debian Security Tracker

lz4→ fixed in1.9.3-2urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y lz4
```

Debian bookworm

Source: Debian Security Tracker

lz4→ fixed in1.9.3-2urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y lz4
```

Debian trixie

Source: Debian Security Tracker

lz4→ fixed in1.9.3-2urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y lz4
```

Alpine v3.20

Source: Alpine secdb

lz4→ fixed in1.9.3-r1
```
apk update && apk add --upgrade lz4
```

Alpine v3.21

Source: Alpine secdb

lz4→ fixed in1.9.3-r1
```
apk update && apk add --upgrade lz4
```

Alpine edge

Source: Alpine secdb

lz4→ fixed in1.9.3-r1
```
apk update && apk add --upgrade lz4
```

Alpine v3.18

Source: Alpine secdb

lz4→ fixed in1.9.3-r1
```
apk update && apk add --upgrade lz4
```

Alpine v3.19

Source: Alpine secdb

lz4→ fixed in1.9.3-r1
```
apk update && apk add --upgrade lz4
```

Are YOU affected by CVE-2021-3520?

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

CVE-2021-3520dropped silently in your distro's update channel. Every new CVE is the same story. StackPatch runs the matcher hourly against all 5 sources and emails the exact remediation when something new applies to one of your servers. $99 lifetime, 50 founder seats, 30-day refund.

See StackPatch ($99 lifetime)