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Vulnerabilities in the PHP language itself, and which PHP versions they affect.

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CVE-2021-21703

HIGH 7.0 CVSS 3.1
Published
October 25, 2021
Last modified
June 17, 2026
NVD status
Modified
Reported by
security@php.net
Weakness
CWE-284, CWE-787
CVSS vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Description

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.

Affected products and versions

  • PHP — From 7.3.0 (including) to 7.3.31 (including)
  • PHP — From 7.4.0 (including) to 7.4.25 (excluding)
  • PHP — From 8.0.0 (including) to 8.0.12 (excluding)

References

  • www.openwall.com http://www.openwall.com/lists/oss-security/2021/10/26/7 Mailing List, Patch, Third Party Advisory
  • bugs.php.net https://bugs.php.net/bug.php?id=81026 Exploit, Issue Tracking, Patch, Vendor Advisory
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2021/10/msg00021.html Mailing List, Third Party Advisory
  • lists.fedoraproject.org https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6PZVLICZUJMXOGWOUWSBAEGIVTF6Y6V3/
  • lists.fedoraproject.org https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JO5RA6YOBGGGKLIA6F6BQRZDDECF5L3R/
  • lists.fedoraproject.org https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PBM3KKB3RY2YPOKNMC4HIH7IH3T3WC74/
  • security.gentoo.org https://security.gentoo.org/glsa/202209-20 Third Party Advisory
  • security.netapp.com https://security.netapp.com/advisory/ntap-20211118-0003/ Third Party Advisory
  • www.debian.org https://www.debian.org/security/2021/dsa-4992 Third Party Advisory
  • www.debian.org https://www.debian.org/security/2021/dsa-4993 Third Party Advisory
  • www.oracle.com https://www.oracle.com/security-alerts/cpuapr2022.html Patch, Vendor Advisory
  • www.oracle.com https://www.oracle.com/security-alerts/cpujan2022.html Patch, Vendor Advisory
  • nvd.nist.gov Official NVD record