#VU52557 Cross-site scripting in MediaWiki - CVE-2021-31551

Vulnerability identifier: #VU52557

Vulnerability risk: Low

CVSSv4.0: 1.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-31551

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
MediaWiki
Web applications / CMS

Vendor: MediaWiki.org

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 in the PageForms extension. A remote 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

MediaWiki: 1.31.0 - 1.35.1

---

External links
https://lists.wikimedia.org/pipermail/mediawiki-announce/2021-April/000274.html
https://phabricator.wikimedia.org/T259433
https://gerrit.wikimedia.org/r/q/I20b63bd38779d2ccbe2d86f9879df85ca3b685f6
https://gerrit.wikimedia.org/r/q/Ibe68b070ee791cd0c8e7f50eb04ac4e066b1512c
https://gerrit.wikimedia.org/r/q/I5e0abbc2f80e6bda255b3b32a4df39a7fe7d3793

---

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.