QID 150525

Date Published: 2022-06-16

QID 150525: PHP Input Validation Vulnerability (CVE-2021-21708)

PHP is a programming language originally designed for use in web-based applications with HTML content. PHP supports a wide variety of platforms and is used by numerous web-based software applications.

In PHP 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.

Affected versions:
7.4.x below 7.4.28
8.0.x below 8.0.16
8.1.x below 8.1.3

QID Detection Logic (Unauthenticated):
This QID checks the HTTP Server header to see if the server is running a vulnerable version of PHP.

Successful exploitation of the vulnerability may allow an attacker to crash the PHP process or Denial of Service (DoS) or Remote Code Execution.

  • CVSS V3 rated as Critical - 9.8 severity.
  • CVSS V2 rated as High - 6.8 severity.
    • Solution
    Customers are advised to upgrade to the latest version of PHP.
    Vendor References

    CVEs related to QID 150525

    CVE-2021-21708 |
    Software Advisories
    Advisory ID Software Component Link
    Sec Bug 81708 URL Logo bugs.php.net/bug.php?id=81708
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