h2. Summary of Vulnerability
Multiple Atlassian Data Center and Server Products use the SnakeYAML library for Java, which is susceptible to a deserialization flaw that can lead to RCE (Remote Code Execution).
(i) Atlassian Cloud sites are not affected by this vulnerability. If your site is accessed via an [atlassian.net|http://atlassian.net/] domain, it is hosted by Atlassian and is not vulnerable to this issue.
h2. Affected Versions
||Product||Affected Versions||
|Bitbucket Data Center
Bitbucket Server| - 7.17.x
Atlassian recommends that you upgrade your instance to one of the versions listed in the “Fixed Versions” table section of this ticket. For full descriptions of the above versions of Bitbucket Data Center and Server, see the [release notes|https://confluence.atlassian.com/bitbucketserver/release-notes]. You can download the latest version of Bitbucket Data Center and Server from the [download center|https://www.atlassian.com/software/bitbucket/download-archives].
For additional details, please see the [full advisory.|https://confluence.atlassian.com/pages/viewpage.action?pageId=1296171009]