File path disclosure of shared files in Richdocuments application

Vulnerability Description

Nextcloud is an open-source, self-hosted productivity platform. The Nextcloud Richdocuments application prior to versions 3.8.6 and 4.2.3 returned verbatim exception messages to the user. This could result in a full path disclosure on shared files. (e.g. an attacker could see that the file `shared.txt` is located within `/files/$username/Myfolder/Mysubfolder/shared.txt`). It is recommended that the Richdocuments application is upgraded to 3.8.6 or 4.2.3. As a workaround, disable the Richdocuments application in the app settings.

References

• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-rjcc-4cgj-6v93
• https://github.com/nextcloud/richdocuments/pull/1760
• https://hackerone.com/reports/1253460