#VU52580 Input validation error in MediaWiki - CVE-2021-31556

Vulnerability identifier: #VU52580

Vulnerability risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-31556

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
MediaWiki
Web applications / CMS

Vendor: MediaWiki.org

Description

The vulnerability allows a remote attacker to compromise the target system.

The vulnerability exists due to the affected software does not validate the oarc_version (aka oauth_registered_consumer.oarc_version) parameter's length in the Oauth extension.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

MediaWiki: 1.31.0 - 1.35.1

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External links
https://lists.wikimedia.org/pipermail/mediawiki-announce/2021-April/000274.html
https://gerrit.wikimedia.org/r/q/I13ff0350a9a0a3cd5ab3e1f82dd0d8d9c13cf9e9

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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.