CVE-2026-101878
Bitwarden Server 2025.6.0 < 2025.6.0 Authentication Bypass via SSO Identifier Truncation
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-303 |
| Vendor | bitwarden |
| Product | bitwarden server |
| Published | Sep 29, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Affected Versions
bitwarden / bitwarden server
2025.6.0 < 2026.5.0
References
sanjokkarki.com.np: https://sanjokkarki.com.np/blog/bitwarden-sso-externalid-truncation github.com: https://github.com/bitwarden/server/releases/tag/v2026.5.0 github.com: https://github.com/bitwarden/server/pull/7501 github.com: https://github.com/bitwarden/server/commit/27ae3d5455f723975fac03819eaeba8710666bc4 vulncheck.com: https://www.vulncheck.com/advisories/bitwarden-server-authentication-bypass-via-sso-identifier-truncation
Credits
Sanjok Karki