Vulnerability identifier: #VU51539

Vulnerability risk: High

CVSSv3.1: 8.8 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2021-27890

CWE-ID: CWE-89

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
MyBB
Other software / Other software solutions

Vendor: MyBB Group

Description

The vulnerability allows a remote attacker to execute arbitrary SQL queries in database.

The vulnerability exists due to insufficient sanitization of user-supplied data within the theme properties included in theme XML files. A remote attacker can send a specially crafted request to the affected application and execute arbitrary SQL commands within the application database.

Successful exploitation of this vulnerability may allow a remote attacker to read, delete, modify data in database and gain complete control over the affected application.

Mitigation
Cybersecurity Help is currently unaware of any official solution to address this vulnerability..

Vulnerable software versions

MyBB: 1.8.0 - 1.8.25

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External links
http://github.com/mybb/mybb/security/advisories/GHSA-r34m-ccm8-mfhq

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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.