Bitwarden Server 2025.6.0 before 2026.5.0 declares the @ExternalId parameter of the User_ReadBySsoUserOrganizationIdExternalId stored procedure as NVARCHAR(50) while the column it queries stores NVARCHAR(300), silently truncating the SSO login identifier on SQL Server deployments and allowing a user whose identity-provider identifier begins with another organization member's full 50-character identifier to authenticate as that member and obtain a victim-scoped access token.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
High
Difficult to exploit
Attack Requirements
None
No additional conditions
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service
CVSS Vector v4.0
Weakness Type (CWE)
Vulnerable Products
bitwarden:bitwarden server
References 5
https://sanjokkarki.com.np/blog/bitwarden-sso-externalid-truncation
Researcher Blog
https://github.com/bitwarden/server/releases/tag/v2026.5.0
Release Notes
https://github.com/bitwarden/server/pull/7501
Pull Request
https://github.com/bitwarden/server/commit/27ae3d5455f723975fac03819eaeba871066…
Patch Commit
https://www.vulncheck.com/advisories/bitwarden-server-authentication-bypass-via…
NVD