Vulnerability identifier: #VU54565

Vulnerability risk: Medium

CVSSv3.1: 6.3 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-21705

CWE-ID: CWE-918

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
PHP
Universal components / Libraries / Scripting languages

Vendor: PHP Group

Description

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

The vulnerability exists due to insufficient validation of user-supplied input. A remote attacker can send a specially crafted HTTP request, bypass the FILTER_VALIDATE_URL and trick the application 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

PHP: 8.0.0 - 8.0.7, 7.4 - 7.4.20, 7.3 - 7.3.28

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External links
http://www.php.net/ChangeLog-8.php#8.0.8
http://www.php.net/ChangeLog-7.php#7.4.21
http://www.php.net/ChangeLog-7.php#7.3.29
http://bugs.php.net/bug.php?id=81122

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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?

No. We are not aware of malware exploiting this vulnerability.