CVE-2015-8994: php

Vulnerability summary

CVE-2015-8994 is a high (CVSS 7.5) vulnerability in php. EPSS estimates a 2.94% chance of exploitation in the next 30 days, higher than 87.1% of scored vulnerabilities. 2 public exploits are recorded.

Timeline

1. 02-03-2017
   PublishedVulnerability first disclosed.
2. 06-08-2024
   Last modifiedVulnerability information updated.

Description

An issue was discovered in PHP 5.x and 7.x, when the configuration uses apache2handler/mod_php or php-fpm with OpCache enabled. With 5.x after 5.6.28 or 7.x after 7.0.13, the issue is resolved in a non-default configuration with the opcache.validate_permission=1 setting. The vulnerability details are as follows. In PHP SAPIs where PHP interpreters share a common parent process, Zend OpCache creates a shared memory object owned by the common parent during initialization. Child PHP processes inherit the SHM descriptor, using it to cache and retrieve compiled script bytecode ("opcode" in PHP jargon). Cache keys vary depending on configuration, but filename is a central key component, and compiled opcode can generally be run if a script's filename is known or can be guessed. Many common shared-hosting configurations change EUID in child processes to enforce privilege separation among hosted users (for example using mod_ruid2 for the Apache HTTP Server, or php-fpm user settings). In these scenarios, the default Zend OpCache behavior defeats script file permissions by sharing a single SHM cache among all child PHP processes. PHP scripts often contain sensitive information: Think of CMS configurations where reading or running another user's script usually means gaining privileges to the CMS database.

• CWE-264Permissions, Privileges, and Access ControlsWeaknesses in this category are related to the management of permissions, privileges, and other security features that are used to perform access control.