This High severity Third-Party Dependency vulnerability was introduced in version 7.19.0 of Confluence Data Center and Server.

This Third-Party Dependency vulnerability, with a CVSS Score of 7.5 and a CVSS Vector of CVSS:3.1/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 Confluence 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:

• Confluence Data Center and Server 7.19: Upgrade to a release greater than or equal to 7.19.16

See the release notes (https://confluence.atlassian.com/doc/confluence-release-notes-327.html). You can download the latest version of Confluence Data Center and Server from the download center (https://www.atlassian.com/software/confluence/download-archives).

The National Vulnerability Database provides the following description for this vulnerability: If Apache Tomcat 8.5.0 to 8.5.82, 9.0.0-M1 to 9.0.67, 10.0.0-M1 to 10.0.26 or 10.1.0-M1 to 10.1.0 was configured to ignore invalid HTTP headers via setting rejectIllegalHeader to false (the default for 8.5.x only), Tomcat did not reject a request containing an invalid Content-Length header making a request smuggling attack possible if Tomcat was located behind a reverse proxy that also failed to reject the request with the invalid header.