CVE-2026-55276

*_This is a vulnerability in a non-Atlassian Jira Software dependency. Atlassian's application of this dependency presents a lower, non-critical assessed risk._* This Critical severity BASM (Broken Authentication & Session Management) vulnerability known as CVE-2026-55276 was introduced in 9.12.0 and later of Jira Software Data Center and Server. This BASM (Broken Authentication & Session Management) vulnerability, with a CVSS Score of 9.1 and a CVSS Vector of CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N allows an unauthenticated attacker to perform actions as another user. 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 9.12: Upgrade to a release greater than or equal to 9.12.37 * Jira Software Data Center and Server 11.3: Upgrade to a release greater than or equal to 11.3.8 * Jira Software Data Center and Server 10.3: Upgrade to a release greater than or equal to 10.3.23 See the release notes ([https://www.atlassian.com/software/jira/download-archives]). You can download the latest version of Jira Software Data Center and Server from the download center ([https://www.atlassian.com/software/jira/download-archives]). The National Vulnerability Database provides the following description for this vulnerability: Always-Incorrect Control Flow Implementation vulnerability in Apache Tomcat meant that special roles and empty authorisation constraints were not included when the effective web.xml was logged. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.22, from 10.1.0-M1 through 10.1.55, from 9.0.0.M1 through 9.0.118, from 8.5.0 through 8.5.100. Other versions that have reached end of support may also be affected. Users are recommended to upgrade to version 11.0.23, 10.1.56 or 9.0.119 which fixes the issue.

EPSS 0.61% · 48.3th percentile