CVE-2015-8994
First published: Thu Mar 02 2017(Updated: )
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.
Credit: cve@mitre.org cve@mitre.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| PHP PHP | >=5.0.0<=5.6.29 | |
| PHP PHP | >=7.0.0<7.0.14 | |
| debian/php5 | ||
| debian/php7.0 | ||
| debian/php7.1 |
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Reference Links
- http://marc.info/?l=php-internals&m=147876797317925&w=2
- http://marc.info/?l=php-internals&m=147921016724565&w=2
- http://openwall.com/lists/oss-security/2017/02/28/1
- http://seclists.org/oss-sec/2016/q4/343
- http://seclists.org/oss-sec/2017/q1/520
- https://bugs.php.net/bug.php?id=69090
- https://ma.ttias.be/a-better-way-to-run-php-fpm/
- http://marc.info/?l=php-internals&m=147876797317925&w=2
- http://marc.info/?l=php-internals&m=147921016724565&w=2
- https://launchpad.net/bugs/cve/CVE-2015-8994
- https://security-tracker.debian.org/tracker/CVE-2015-8994
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-8994
- https://nvd.nist.gov/vuln/detail/CVE-2015-8994
- https://ubuntu.com/security/CVE-2015-8994
Frequently Asked Questions
What is the vulnerability ID for this issue?
The vulnerability ID for this issue is CVE-2015-8994.
What is the severity of CVE-2015-8994?
CVE-2015-8994 has a severity rating of 7.5 (high).
What versions of PHP are affected by CVE-2015-8994?
Versions of PHP 5.x (after 5.6.28) and PHP 7.x (after 7.0.13) are affected by CVE-2015-8994.
How can I mitigate the vulnerability in PHP?
Mitigate the vulnerability in PHP by using a non-default configuration with the opcache.validate_permission=1 setting.
Where can I find more information about CVE-2015-8994?
You can find more information about CVE-2015-8994 at the following references: [Link 1](http://openwall.com/lists/oss-security/2017/02/28/1), [Link 2](http://seclists.org/oss-sec/2016/q4/343), [Link 3](http://seclists.org/oss-sec/2017/q1/520).
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