CVE-2026-101878
Bitwarden Server 2025.6.0 < 2025.6.0 Authentication Bypass via SSO Identifier Truncation
- State
- Published
- Severity
- 7.7 High
- Published
- Sep 29, 2026
- Updated
- Oct 1, 2026
- Reserved
- Sep 28, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 7.7 High | CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N | VulnCheck |
| 3.1 | 7.5 High | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H | VulnCheck |
Weaknesses
- CWE-303 Incorrect Implementation of Authentication Algorithm
Affected Products
| Product | Versions |
|---|---|
bitwarden serverbitwarden |
|
References
- Researcher Blogtechnical-descriptionexploit
- Release Notesrelease-notes
- Pull Requestissue-tracking
- Patch Commitpatch
- https://www.vulncheck.com/advisories/bitwarden-server-authentication-bypass-via-sso-identifier-truncationthird-party-advisory
Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.