This High severity Third-Party Dependency vulnerability was introduced in versions 8.20.0, 9.4.0, 9.5.0, 9.6.0, 9.7.0, 9.8.0, 9.9.0, 9.10.0, 9.10.1, and 9.11.0 of Jira Software Data Center and Server.

This Third-Party Dependency vulnerability, with a CVSS Score of 7.5 and a CVSS Vector of CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N allows an unauthenticated attacker to expose assets in your environment susceptible to exploitation which has no impact to confidentiality, high impact to integrity, no impact to availability, and requires no user interaction.

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

• Jira Software Data Center and Server 9.10: Upgrade to a release greater than or equal to 9.10.2

• Jira Software Data Center and Server 9.11: Upgrade to a release greater than or equal to 9.11.1

See the release notes. You can download the latest version of Jira Software Data Center and Server from the download center.

The National Vulnerability Database provides the following description for this vulnerability: In Eclipse Jetty, versions 9.2.x and older, 9.3.x (all configurations), and 9.4.x (non-default configuration with RFC2616 compliance enabled), HTTP/0.9 is handled poorly. An HTTP/1 style request line (i.e. method space URI space version) that declares a version of HTTP/0.9 was accepted and treated as a 0.9 request. If deployed behind an intermediary that also accepted and passed through the 0.9 version (but did not act on it), then the response sent could be interpreted by the intermediary as HTTP/1 headers. This could be used to poison the cache if the server allowed the origin client to generate arbitrary content in the response.