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TI-2021-04783 Aliases CVE-2021-21703GHSA-h8qx-36w6-3rc4

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

Priority LOW 37CWE-284Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
High
Impact type
Security bypass, Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 3 fixed, 3 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-284, CWE-787 and the CVSS impact.

Summary

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.

Why it matters now

EPSS 0.01426 73rd percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial PHP (PHP Group): 7.4.25, 8.0.12Red Hat: 2 advisoriesRed Hat: 3 fixed, 3 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
PHP GroupPHP7.3.x – 7.3.31; 7.4.x to before 7.4.25; 8.0.X to before 8.0.127.4.25, 8.0.12Patch availableCNA
  • PHP VendorPHP Group Affected 7.3.x – 7.3.31; 7.4.x to before 7.4.25; 8.0.X to before 8.0.12 Fixed in 7.4.25, 8.0.12 Patch available CNA

CPE configurations NVD · 9

CPEVersionsRoleVendor
cpe:2.3:a:php:php:*:*:*:*:*:*:*:*7.3.0 – 7.3.31; 7.4.0 to before 7.4.25; 8.0.0 to before 8.0.12VulnerablePHP
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*9.0VulnerableDebian
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*10.0VulnerableDebian
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*11.0VulnerableDebian
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*33VulnerableFedoraproject
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*34VulnerableFedoraproject
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*35VulnerableFedoraproject
cpe:2.3:a:netapp:clustered_data_ontap:-:*:*:*:*:*:*:*not specified by NVDVulnerableNetApp
cpe:2.3:a:oracle:communications_diameter_signaling_router:*:*:*:*:*:*:*:*8.0.0.0 – 8.5.0.2VulnerableOracle
  • cpe:2.3:a:php:php:*:*:*:*:*:*:*:* Versions 7.3.0 – 7.3.31; 7.4.0 to before 7.4.25; 8.0.0 to before 8.0.12 Vulnerable ·PHP
  • cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
  • cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Debian
  • cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* Versions 11.0 Vulnerable ·Debian
  • cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* Versions 33 Vulnerable ·Fedoraproject
  • cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* Versions 34 Vulnerable ·Fedoraproject
  • cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* Versions 35 Vulnerable ·Fedoraproject
  • cpe:2.3:a:netapp:clustered_data_ontap:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
  • cpe:2.3:a:oracle:communications_diameter_signaling_router:*:*:*:*:*:*:*:* Versions 8.0.0.0 – 8.5.0.2 Vulnerable ·Oracle

Remediation

  • Fix · CNA PHP (PHP Group) Fixed in 7.4.25, 8.0.12

Red Hat 2 advisories

  • RHSA-2022:5491 Released 2022-07-04 · Red Hat rating Important
    rh-php73-php security and bug fix update
    • Red Hat Software Collections for RHEL Workstation(v. 7) rh-php73-php-7.3.33-1.el7, rh-php73-php-bcmath-7.3.33-1.el7, rh-php73-php-cli-7.3.33-1.el7 +26
    • Red Hat Software Collections for RHEL(v. 7) rh-php73-php-7.3.33-1.el7, rh-php73-php-bcmath-7.3.33-1.el7, rh-php73-php-cli-7.3.33-1.el7 +26
  • RHSA-2022:1935 Released 2022-05-10 · Red Hat rating Moderate
    php:7.4 security update
    • Red Hat Enterprise Linux AppStream (v. 8) apcu-panel-5.1.18-1.module+el8.3.0+6678+b09f589e.noarch::php:7.4, libzip-1.6.1-1.module+el8.3.0+6678+b09f589e.aarch64::php:7.4, libzip-1.6.1-1.module+el8.3.0+6678+b09f589e.ppc64le::php:7.4 +47

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 7AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 8AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux AppStream (v. 8)Fixed RHSA-2022:1935
Red Hat Software Collections for RHEL Workstation(v. 7)Fixed RHSA-2022:5491
Red Hat Software Collections for RHEL(v. 7)Fixed RHSA-2022:5491
Not affected: 1 product
  • Red Hat Enterprise Linux 9

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-21703
  2. 2026-10-03 Alias added: GHSA-h8qx-36w6-3rc4

References

Exploit 1

Patch 3

Advisory 8

  • TI-2024-04260 Argument Injection in PHP-CGI KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-78794 PHP remote code execution via stale global state KEVCVSS 4.0CRITICAL 9.2
  • TI-2026-78793 Out-of-memory handling flaw in PHP allows remote code execution KEVCVSS 4.0CRITICAL 9.2
  • TI-2024-01743 Command injection via array-ish $command parameter of proc_open() CVSS 3.1CRITICAL 9.4
  • TI-2022-13555 PDO::quote() may return unquoted string CVSS 3.1CRITICAL 9.1
  • TI-2024-10408 Reference counting in php_request_shutdown causes Use-After-Free CVSS 4.0CRITICAL 9.2
See all 107 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences