We have identified and fixed a vulnerability in Stash which allowed unauthenticated users to commit actions on behalf of any other authorised user. In order to exploit this vulnerability, an attacker requires access to your Stash web interface.
The Stash server is only vulnerable if it has been configured to be a part of an Application link with Trusted Applications authentication.
The vulnerability affects all supported versions of Stash up to and including 2.5.3, 2.6.4, 2.7.5 and 2.8.3. It has been fixed in the Stash security patch releases 2.5.4, 2.6.5, 2.7.6, 2.8.4. The vulnerability does not affect the Stash 2.9 and 2.10 releases.
For more information, see our [security advisory|https://confluence.atlassian.com/display/STASH/Stash+security+advisory+2014-02-26].