CVE-2021-21708 UAF due to php_filter_float() failing

2022-02-2708:00:12

CWE-416

php

www.cve.org

cve-2021-21708; uaf; php_filter_float(); php 7.4.x; php 8.0.x; php 8.1.x; filter_validate_float; memory after free; rce; min/max limits.

CVSS3

8.2

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

HIGH

Availability Impact

LOW

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L

AI Score

9.7

Confidence

High

EPSS

0.003

Percentile

71.2%

JSON

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.

CNA Affected

[
  {
    "product": "PHP",
    "vendor": "PHP Group",
    "versions": [
      {
        "lessThan": "7.4.28",
        "status": "affected",
        "version": "7.4.x",
        "versionType": "custom"
      },
      {
        "lessThan": "8.0.16",
        "status": "affected",
        "version": "8.0.X",
        "versionType": "custom"
      },
      {
        "lessThan": "8.1.3",
        "status": "affected",
        "version": "8.1.X",
        "versionType": "custom"
      }
    ]
  }
]