This High severity Information Disclosure vulnerability was introduced in version 11.3.0 of Jira Service Management Data Center.

This Information Disclosure 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:H/I:N/A:N allows an unauthenticated attacker to expose assets in your environment susceptible to exploitation, which has high impact to confidentiality, no impact to integrity, no impact to availability, and requires no user interaction.

Atlassian recommends that Jira Service Management 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:

• Jira Service Management Data Center 11.3: Upgrade to a release greater than or equal to 11.3.5

See the release notes
(https://confluence.atlassian.com/servicemanagement/jira-service-management-release-notes-780083086.html). You can
download the latest version of Jira Service Management Data Center from the download center
(https://www.atlassian.com/software/jira/service-management/download-archives).

The National Vulnerability Database provides the following description for this vulnerability:

http-cache-semantics through 4.2.0 fails to properly validate security-zeroed cache entries when processing client max-stale directives, allowing unauthenticated attackers to retrieve cached responses belonging to other users. Attackers can request the same URL with a large max-stale value to obtain another user's Set-Cookie session credentials from shared-cache entries that were deliberately zeroed for security reasons.