CVE-2021-21708 is a vulnerability in PHP
Published on February 27, 2022
UAF due to php_filter_float() failing
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.
Vulnerability Analysis
CVE-2021-21708 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, a high impact on integrity, and a small impact on availability.
Weakness Type
What is a Dangling pointer Vulnerability?
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.
CVE-2021-21708 has been classified to as a Dangling pointer vulnerability or weakness.
Products Associated with CVE-2021-21708
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Affected Versions
PHP Group PHP:- Version 7.4.x and below 7.4.28 is affected.
- Version 8.0.X and below 8.0.16 is affected.
- Version 8.1.X and below 8.1.3 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.