#VU56459 Cross-site scripting in BookStack - CVE-2021-3768

Vulnerability identifier: #VU56459

Vulnerability risk: Low

CVSSv4.0: 0.4 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-3768

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
BookStack
Client/Desktop applications / Other client software

Vendor: Dan Brown

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. A remote authenticated attacker can trick the victim to follow a specially crafted link and execute arbitrary HTML and script code in user's browser in context of vulnerable website.

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 updates from vendor's website.

Vulnerable software versions

BookStack: 21.04 - 21.08.1

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External links
https://github.com/bookstackapp/bookstack/commit/5e6092aaf8fd420202016038286554860bf8ea64
https://huntr.dev/bounties/64a0229f-ff5e-4c64-b83e-9bfc0698a78e

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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.