Vulnerability identifier: #VU16917

Vulnerability risk: Low

CVSSv3.1: 6.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:C]

CVE-ID: N/A

CWE-ID: CWE-120

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 cause DoS condition on the target system.

The weakness exists due to boundary error when using mb regex functions such as mb_ereg and mb_split, with a pattern containing (?i) and a string ending with an incomplete multibyte character. A remote attacker can trigger buffer overflow in multibyte case folding - unicode and cause the service to crash.

Mitigation
The vulnerability has been fixed in the versions 5.6.40, 7.1.26, 7.3.1.

Vulnerable software versions

PHP: 7.3.0 - 7.3.0beta3, 7.1.0 - 7.1.25, 5.6.0 - 5.6.39, 5.5.6

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External links
http://bugs.php.net/bug.php?id=77394

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