Description

Two high-severity vulnerabilities have been identified in Vaultwarden, an open-source Bitwarden-compatible password manager server. The flaws allow attackers with limited manager-level permissions to bypass authorization checks, escalate privileges, and access sensitive credential collections. These issues affect Vaultwarden version 1.35.3 and can be exploited remotely without user interaction, posing significant risks to organizations relying on the platform for credential management. The first vulnerability, CVE-2026-27803, stems from improper authorization enforcement in Vaultwarden’s collection management logic. Manager-level accounts are typically restricted from modifying collections unless explicitly granted administrative privileges. However, testing revealed that managers with basic access to a collection could still perform administrative actions such as modifying user assignments or deleting collections even when the manage=false restriction is applied. By sending specially crafted HTTP requests, attackers can bypass the intended access control mechanisms and manipulate sensitive organizational resources. The second flaw, CVE-2026-27802, involves the bulk-access API. A manager account configured without global access permissions (access_all=false) can exploit this endpoint to modify assignments for collections that were never granted to them. Through bulk API requests, attackers can change the assignment flag from false to true, effectively granting themselves unauthorized access to restricted collections. Notably, the regular single-update API properly blocks such attempts with a 401 Unauthorized response, but the bulk endpoint bypasses this validation. Once the bulk request succeeds, the regular API begins accepting the unauthorized changes, confirming a critical authorization gap at the HTTP layer.