CVE-2015-9253

Severity: medium (CVSS 6.5 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 4.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2018-02-19 · updated 2026-06-17
Weakness: CWE-400

Description

An issue was discovered in PHP 7.3.x before 7.3.0alpha3, 7.2.x before 7.2.8, and before 7.1.20. The php-fpm master process restarts a child process in an endless loop when using program execution functions (e.g., passthru, exec, shell_exec, or system) with a non-blocking STDIN stream, causing this master process to consume 100% of the CPU, and consume disk space with a large volume of error logs, as demonstrated by an attack by a customer of a shared-hosting facility.

Affected products

PHP: before 7.1.20; from 7.2.0 before 7.2.8; 7.3.0-alpha1, 7.3.0-alpha2 — fixed in 7.1.20, 7.2.8

How to fix

Upgrade to a fixed version: PHP 7.1.20, 7.2.8. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2015-9253 or the next vulnerability affects your stack