DEBIAN-CVE-2021-21703

Advisory lineage Upstream: 1 Downstream: 3
Upstream
CVE-2021-21703
Published: 25 Oct 2021, 06:15
Last modified:28 Apr 2026, 20:22

Vulnerability Summary

Overall Risk (default)
medium
28/100
CVSS Score
7 HIGH
3.1 (osv_debian)
EPSS Score
No data
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

25 Oct 2021, 06:15
Published
Vulnerability first disclosed
28 Apr 2026, 20:22
Last Modified
Vulnerability information updated

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.

CVSS Metrics

  • v3.1•HIGH•Score: 7CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected Systems

  • debian•php7.4

    < 7.4.25-1+deb11u1

References (1)