Php-fpm Remote Code Execution Vulnerability (CVE-2019-11043) Threat Alert

Php-fpm Remote Code Execution Vulnerability (CVE-2019-11043) Threat Alert

outubro 29, 2019 | Adeline Zhang


Recently, security researchers have published a vulnerability in php-fpm (CVE-2019-11043) that could lead to remote code execution in certain Nginx configurations.

The vulnerability exists in the file sapi/fpm/fpm/fpm_main.c (, which assumes the prefix of env_path_info Equal to the path of the php script, but in fact the code does not check if this assumption is met, and the lack of this check will invalidate the pointer in the “path_info” variable. In some Nginx configurations, an attacker can use a line break (encoded at %0a) to destroy the regexp in the `fastcgi_split_path_info` directive, which can cause a null PATH_INFO, which triggers the vulnerability.

It is understood that the vulnerability was discovered by researcher Andrew Danau during a CTF game. When he sent %0a to the server URL, the server returned an exception and discovered the vulnerability after further research.


Affected Versions 

In the Nginx + php-fpm environment, all of the PHP 7+ versions are affected (PHP 7.0, PHP 7.1, PHP 7.2, PHP 7.3) using the following Nginx configuration, and currently crash on PHP 5.6.

The specific Nginx configuration is as follows:

   location ~ [^/]\.php(/|$) {

fastcgi_split_path_info ^(.+?\.php)(/.*)$;

fastcgi_param PATH_INFO       $fastcgi_path_info;

fastcgi_pass   php:9000;



Security Recommendations

  • PHP has released a patch on October 12 (see the reference below) It is recommended that affected users should upgrade your system to prevent against this vulnerability.
  • Check the Nginx configuration. If the above vulnerable configuration exists, it is recommended to delete:

fastcgi_split_path_info ^(.+?\.php)(/.*)$;

fastcgi_param PATH_INFO       $fastcgi_path_info;



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