CVE-2021-21708 · cross-distro fix matrix

CVE-2021-21708: In PHP versions 7.4.x below 7.4.28, 8.0.x below 8.0.16, and 8.1.x below 8.1.3, when using filter functions with FILTER_VALIDATE_FLOAT filter and min/max limits, if the filter fails, there is a possibility to trigger use of allocated memory after free, which can result it crashes, and potentially in

Affects 1 Linux release across 1 (distro × package) combinations.

Fix per ecosystem

Each block below is a distro release where CVE-2021-21708 has a known fix. Run the listed command on that distro to remediate.

Debian bullseye

Source: Debian Security Tracker

php7.4→ fixed in7.4.28-1+deb11u1urgency: not yet assigned
```
sudo apt-get install --only-upgrade -y php7.4
```

Are YOU affected by CVE-2021-21708?

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-2021-21708dropped 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.

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