Advisory Details

This vulnerability allows remote attackers to bypass authentication on affected installations of Vinchin Backup and Recovery. Authentication is not required to exploit this vulnerability.

The specific flaw exists within the handling of API access tokens. The issue results from the use of a hard-coded cryptographic key to validate the access token. An attacker can leverage this vulnerability to bypass authentication on the system.

This vulnerability is being disclosed publicly without a patch in accordance with the ZDI 120 day deadline.

08/04/21 – ZDI requested PSIRT contact
08/12/21 – ZDI requested an update
08/16/21 – Vendor sent an automation reply that a ticket had been created
09/06/21 – Vendor mentioned that a salesperson would be responding soon
09/06/21 – ZDI asked them to provide PGP key to send them the vulnerability reports, but there was no reply
10/20/21 – ZDI notified the vendor of the intention to publish the case as a 0-day advisory on 10/27/21

-- Mitigation:
Given the nature of the vulnerability the only salient mitigation strategy is to restrict interaction with the application.

• 2021-10-27 - Vulnerability reported to vendor
• 2021-10-27 - Coordinated public release of advisory