#VU56678 Server-Side Request Forgery (SSRF) in Apache HTTP Server - CVE-2021-40438

Vulnerability identifier: #VU56678

Vulnerability risk: High

CVSSv4.0: 8.8 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:L/SI:N/SA:N/E:A/U:Amber]

CVE-ID: CVE-2021-40438

CWE-ID: CWE-918

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
Apache HTTP Server
Server applications / Web servers

Vendor: Apache Foundation

Description

The disclosed vulnerability allows a remote attacker to perform SSRF attacks.

The vulnerability exists due to insufficient validation of user-supplied input within the mod_proxy module in Apache HTTP Server. A remote attacker can send a specially crafted HTTP request with a chosen uri-path and trick the web server to initiate requests to arbitrary systems.

Successful exploitation of this vulnerability may allow a remote attacker gain access to sensitive data, located in the local network or send malicious requests to other servers from the vulnerable system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Apache HTTP Server: 2.4.0 - 2.4.48

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External links
https://httpd.apache.org/security/vulnerabilities_24.html

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.