This High severity XSS (Cross Site Scripting) vulnerability was introduced in versions 8.19.0, 9.0.1, and 10.0.0 of Bitbucket Data Center.

This XSS (Cross Site Scripting) vulnerability, with a CVSS Score of 7.3 and a CVSS Vector of CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L allows an unauthenticated attacker to potentially run arbitrary code on client browsers which has low impact to confidentiality, low impact to integrity, low impact to availability, and requires no user interaction.

Atlassian recommends that Bitbucket Data Center customers upgrade to latest version, if you are unable to do so, upgrade your instance to one of the specified supported fixed versions:

• Bitbucket Data Center 9.4: Upgrade to a release greater than or equal to 9.4.18

• Bitbucket Data Center 10.2: Upgrade to a release greater than or equal to 10.2.2

See the release notes (https://confluence.atlassian.com/bitbucketserver/release-notes). You can download the latest version of Bitbucket Data Center from the download center (https://www.atlassian.com/software/bitbucket/download-archives).

The National Vulnerability Database provides the following description for this vulnerability: DOMPurify is a DOM-only, super-fast, uber-tolerant XSS sanitizer for HTML, MathML and SVG. It has been discovered that malicious HTML using special nesting techniques can bypass the depth checking added to DOMPurify in recent releases. It was also possible to use Prototype Pollution to weaken the depth check. This renders dompurify unable to avoid cross site scripting (XSS) attacks. This issue has been addressed in versions 2.5.4 and 3.1.3 of DOMPurify. All users are advised to upgrade. There are no known workarounds for this vulnerability.