Denial of service in PHP



Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2021-21708
CWE-ID CWE-416
Exploitation vector Network
Public exploit Public exploit code for vulnerability #1 is available.
Vulnerable software
 PHP
Universal components / Libraries / Scripting languages

Vendor PHP Group

Security Bulletin

This security bulletin contains one medium risk vulnerability.

1) Use-after-free

EUVDB-ID: #VU60707

Risk: Medium

CVSSv4.0: 5.5 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2021-21708

CWE-ID: CWE-416 - Use After Free

Exploit availability: Yes

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a use-after-free error within the "php_filter_float()" function. A remote attacker can pass specially crafted input to the application that uses the affected PHP function, trigger a use-after-free error and crash the php-fpm process.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

PHP: 7.4 - 8.1.2

CPE2.3 External links

https://bugs.php.net/bug.php?id=81708
https://www.php.net/ChangeLog-8.php#8.1.3
https://www.php.net/ChangeLog-8.php#8.0.16
https://www.php.net/ChangeLog-7.php#7.4.28


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. However, proof of concept for this vulnerability is available.



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