Vulnerability identifier: #VU4660

Vulnerability risk: Low

CVSSv3.1: 5.6 [CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-5494

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
b2evolution
Web applications / CMS

Vendor: b2evolution.net

Description

The disclosed vulnerability allows a remote attacker to perform cross-site scripting (XSS) attacks.

The vulnerability exists due to insufficient sanitization of user-supplied data when uploading .swf files for avatar and comments. A remote authenticated attacker can upload malicious .swf file, containing arbitrary JavaScript code and execute it in user's browser in context of vulnerable website, when the victim visits a page with uploaded file.

Successful exploitation of this vulnerability may allow a remote attacker to steal potentially sensitive information, change appearance of the web page, perform phishing and drive-by-download attacks.

Mitigation
Install update from vendor's GIT repository.

Vulnerable software versions

b2evolution: 6.8.1 - 6.8.3

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External links
http://github.com/b2evolution/b2evolution/issues/34
http://github.com/b2evolution/b2evolution/commit/261dbd5b294e707af766691e65a177a290314a6e

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

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