#VU54566 Stack-based buffer overflow in PHP - CVE-2021-21704

Vulnerability identifier: #VU54566

Vulnerability risk: High

CVSSv4.0: 7.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2021-21704

CWE-ID: CWE-121

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
PHP
Universal components / Libraries / Scripting languages

Vendor: PHP Group

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

Multiple boundary errors exists within firebird_info_cb(), firebird_handle_doer(), firebird_stmt_execute(), and firebird_fetch_blob() function. A remote attacker can pass specially crafted input to the application, trigger a stack-based buffer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

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

---

External links
https://www.php.net/ChangeLog-8.php#8.0.8
https://www.php.net/ChangeLog-7.php#7.4.21
https://www.php.net/ChangeLog-7.php#7.3.29
https://bugs.php.net/76448
https://bugs.php.net/76449
https://bugs.php.net/76450
https://bugs.php.net/76452

---

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.