CVE-2021-21708

Description

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 overwrite of other memory chunks and RCE. This issue affects: code that uses FILTER_VALIDATE_FLOAT with min/max limits.

How to fix CVE-2021-21708

To remediate CVE-2021-21708, upgrade the affected package to a fixed version below.

• —upgrade to 7.4.28 or later
• —upgrade to 7.4.28 or later
• —upgrade to 7.4.28 or later
• —upgrade to 7.4.28-1+deb11u1 or later

Is CVE-2021-21708 being exploited?

Low — EPSS is 0.2%, meaning exploitation activity has not been observed at scale.

Affected packages (4)

• >= 7.4.0, < 7.4.28, >= 8.0.0, < 8.0.16, >= 8.1.0, < 8.1.3
• >= 7.4.0, < 7.4.28, >= 8.0.0, < 8.0.16, >= 8.1.0, < 8.1.3
• >= 7.4.0, < 7.4.28, >= 8.0.0, < 8.0.16, >= 8.1.0, < 8.1.3
• from 0, < 7.4.28-1+deb11u1

CVSS scores

References (5)

• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2021-21708
• WEBbugs.php.net/bug.php?id=81708
• WEBnvd.nist.gov/vuln/detail/CVE-2021-21708
• WEBsecurity.gentoo.org/glsa/202209-20
• WEB