CVE-2021-21703 PHP-FPM memory access in root process leading to privilege escalation

2021-10-1800:00:00

CWE-284

CWE-787

php

www.cve.org

7.8 High

CVSS3

Attack Vector

LOCAL

Attack Complexity

HIGH

Privileges Required

LOW

User Interaction

NONE

Scope

CHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

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

7.7 High

AI Score

Confidence

High

0.001 Low

EPSS

Percentile

51.0%

JSON

In PHP versions 7.3.x up to and including 7.3.31, 7.4.x below 7.4.25 and 8.0.x below 8.0.12, when running PHP FPM SAPI with main FPM daemon process running as root and child worker processes running as lower-privileged users, it is possible for the child processes to access memory shared with the main process and write to it, modifying it in a way that would cause the root process to conduct invalid memory reads and writes, which can be used to escalate privileges from local unprivileged user to the root user.

CNA Affected

[
  {
    "product": "PHP",
    "vendor": "PHP Group",
    "versions": [
      {
        "lessThanOrEqual": "7.3.31",
        "status": "affected",
        "version": "7.3.x",
        "versionType": "custom"
      },
      {
        "lessThan": "7.4.25",
        "status": "affected",
        "version": "7.4.x",
        "versionType": "custom"
      },
      {
        "lessThan": "8.0.12",
        "status": "affected",
        "version": "8.0.X",
        "versionType": "custom"
      }
    ]
  }
]