Collabora Online is a collaborative online office suite based on LibreOffice technology. Each document in Collabora Online is opened by a separate "Kit" instance in a different "jail" with a unique directory "jailID" name. For security reasons, this directory name is randomly generated and should not be given out to the client. In affected versions of Collabora Online it is possible to use the CELL() function, with the "filename" argument, in the spreadsheet component to get a path which includes this JailID. The impact of this vulnerability in its own is low because it requires to be chained with another vulnerability. Users should upgrade to Collabora Online 23.05.9; Collabora Online 22.05.22; Collabora Online 21.11.10 or higher. There are no known workarounds for this vulnerability.
https://github.com/LibreOffice/online/blob/master/wsd/README
https://github.com/CollaboraOnline/online/security/advisories/GHSA-2fh2-ppjf-p3xv