Linux Distros Unpatched Vulnerability : CVE-2021-21703

high Nessus Plugin ID 223676

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Synopsis

The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.

Description

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

- 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.
(CVE-2021-21703)

Note that Nessus relies on the presence of the package as reported by the vendor.

Solution

There is no known solution at this time.

Plugin Details

Severity: High

ID: 223676

File Name: unpatched_CVE_2021_21703.nasl

Version: 1.4

Type: local

Agent: unix

Family: Misc.

Published: 3/4/2025

Updated: 9/29/2025

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.4

CVSS v2

Risk Factor: Medium

Base Score: 6.9

Temporal Score: 5.4

Vector: CVSS2#AV:L/AC:M/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2021-21703

CVSS v3

Risk Factor: High

Base Score: 7

Temporal Score: 6.3

Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:centos:centos:php-ldap, p-cpe:/a:centos:centos:php-bcmath, p-cpe:/a:redhat:enterprise_linux:php-json, p-cpe:/a:redhat:enterprise_linux:php-fpm, p-cpe:/a:redhat:enterprise_linux:php-pecl-apcu, p-cpe:/a:redhat:enterprise_linux:php-bcmath, p-cpe:/a:centos:centos:php-gd, p-cpe:/a:redhat:enterprise_linux:php-pecl-xdebug3, p-cpe:/a:redhat:enterprise_linux:php-pear, p-cpe:/a:centos:centos:php-recode, p-cpe:/a:redhat:enterprise_linux:php, p-cpe:/a:redhat:enterprise_linux:php-ffi, p-cpe:/a:redhat:enterprise_linux:php-gd, p-cpe:/a:redhat:enterprise_linux:php-mysqlnd, p-cpe:/a:centos:centos:php-json, p-cpe:/a:redhat:enterprise_linux:php-odbc, p-cpe:/a:centos:centos:php-mbstring, p-cpe:/a:redhat:enterprise_linux:php-mbstring, p-cpe:/a:centos:centos:php-process, p-cpe:/a:redhat:enterprise_linux:php-pecl-zip, p-cpe:/a:centos:centos:php-common, p-cpe:/a:redhat:enterprise_linux:php-pecl-apcu-devel, p-cpe:/a:centos:centos:php-pear, p-cpe:/a:centos:centos:php-soap, p-cpe:/a:centos:centos:php-pecl-apcu, p-cpe:/a:centos:centos:php-pecl-xdebug, p-cpe:/a:redhat:enterprise_linux:php-opcache, p-cpe:/a:centos:centos:php-dba, p-cpe:/a:centos:centos:libzip, p-cpe:/a:centos:centos:php-dbg, p-cpe:/a:centos:centos:php-pgsql, p-cpe:/a:redhat:enterprise_linux:php-snmp, p-cpe:/a:redhat:enterprise_linux:libzip-tools, p-cpe:/a:centos:centos:php-pecl-zip, p-cpe:/a:centos:centos:libzip-tools, p-cpe:/a:centos:centos:php, p-cpe:/a:centos:centos:php-odbc, p-cpe:/a:centos:centos:php-intl, p-cpe:/a:centos:centos:php-mysqlnd, p-cpe:/a:centos:centos:php-enchant, p-cpe:/a:centos:centos:apcu-panel, p-cpe:/a:centos:centos:php-pecl-rrd, p-cpe:/a:centos:centos:php-xmlrpc, p-cpe:/a:redhat:enterprise_linux:php-xml, p-cpe:/a:redhat:enterprise_linux:php-cli, p-cpe:/a:redhat:enterprise_linux:php-enchant, p-cpe:/a:redhat:enterprise_linux:php-gmp, p-cpe:/a:redhat:enterprise_linux:libzip-devel, p-cpe:/a:centos:centos:php-embedded, cpe:/o:redhat:enterprise_linux:8, p-cpe:/a:redhat:enterprise_linux:php-recode, p-cpe:/a:centos:centos:php-pecl-apcu-devel, p-cpe:/a:redhat:enterprise_linux:php-dbg, p-cpe:/a:centos:centos:php-snmp, p-cpe:/a:redhat:enterprise_linux:apcu-panel, p-cpe:/a:centos:centos:php-ffi, p-cpe:/a:redhat:enterprise_linux:php-common, p-cpe:/a:redhat:enterprise_linux:libzip, p-cpe:/a:redhat:enterprise_linux:php-pecl-xdebug, p-cpe:/a:centos:centos:php-fpm, p-cpe:/a:centos:centos:php-opcache, p-cpe:/a:redhat:enterprise_linux:php-embedded, p-cpe:/a:redhat:enterprise_linux:php-devel, cpe:/o:centos:centos:8, p-cpe:/a:centos:centos:php-xml, p-cpe:/a:centos:centos:php-devel, p-cpe:/a:redhat:enterprise_linux:php-pecl-rrd, p-cpe:/a:redhat:enterprise_linux:php-ldap, p-cpe:/a:centos:centos:libzip-devel, p-cpe:/a:redhat:enterprise_linux:php-xmlrpc, p-cpe:/a:centos:centos:php-pdo, p-cpe:/a:redhat:enterprise_linux:php-intl, p-cpe:/a:redhat:enterprise_linux:php-soap, p-cpe:/a:centos:centos:php-cli, p-cpe:/a:centos:centos:php-gmp, p-cpe:/a:redhat:enterprise_linux:php-pdo, p-cpe:/a:centos:centos:php-pecl-xdebug3, p-cpe:/a:redhat:enterprise_linux:php-dba, p-cpe:/a:redhat:enterprise_linux:php-pgsql, p-cpe:/a:redhat:enterprise_linux:php-process

Required KB Items: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier

Exploit Available: true

Exploit Ease: Exploits are available

Vulnerability Publication Date: 10/18/2021

Reference Information

CVE: CVE-2021-21703

Detections

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