This High severity BASM (Broken Authentication & Session Management) vulnerability known as CVE-2026-12816 was introduced in 6.1.0 and later of Crowd Data Center and Server.

This BASM (Broken Authentication & Session Management) vulnerability, with a CVSS Score of 8.7 and a CVSS Vector of CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Amber allows an unauthenticated attacker to perform actions as another user.

Atlassian recommends that Crowd 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:

• Crowd Data Center and Server 7.2: Upgrade to a release greater than or equal to 7.2.3

See the release notes (https://confluence.atlassian.com/crowd/crowd-release-notes-199094.html). You can download the latest version of Crowd Data Center and Server from the download center (https://www.atlassian.com/software/crowd/download-archive).

The National Vulnerability Database provides the following description for this vulnerability: In Bouncy Castle for Java before 1.85, IESEngine stream-mode MAC forgery via length-dependent KDF split. This issue also affects Bouncy Castle for Java LTS before 2.73.12.