#VU9867 Improper restriction of XML external entity reference (XXE) in PHP - CVE-2015-8866

Vulnerability identifier: #VU9867

Vulnerability risk: Medium

CVSSv4.0: 1.7 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:L/SC:L/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2015-8866

CWE-ID: CWE-611

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 perform XXE. attcks.

The vulnerability exists in ext/libxml/libxml.c when using PHP-FPM due to improper isolation of each threat from libxml_disable_entity_loader changes in other threads. A remote attacker can perform XML External Entity (XXE) and XML Entity Expansion (XEE) attacks via a crafted XML document.

Note: this vulnerability is known at least since 2013 and it was patched several times.

Mitigation
Update to version 7.0.27.

Vulnerable software versions

PHP: 5.4.15 - 5.4.44, 5.5.0 - 5.5.38, 5.6.0 - 5.6.32, 7.0.0 - 7.0.26, 7.1.0 - 7.1.12, 7.2.0

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External links
https://www.openwall.com/lists/oss-security/2016/04/24/1
https://git.php.net/?p=php-src.git;a=commit;h=de31324c221c1791b26350ba106cc26bad23ace9
https://www.php.net/ChangeLog-5.php
https://bugs.php.net/bug.php?id=64938

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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.