CVE-2026-101878
Bitwarden Server 2025.6.0 < 2025.6.0 Authentication Bypass via SSO Identifier Truncation
bitwarden bitwarden server
CVSS
7.7HighExploitationPublic exploit codeCISA's assessment says proof of concept code is public, assessed 29 Sep 2026. Not in the KEV catalogCISA via CVE List
Exploit odds (EPSS)0.26%Chance of exploitation activity in the next 30 days, higher than 16% of CVEs. Scored 23 Oct 2026FIRST EPSS
What fixes it
- 2026.5.0bitwarden serverCVE List
A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.
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.
Text from CVE List
Affected versions 1
- bitwarden serveraffected: 2025.6.0 before 2026.5.0CVE List
References 5
- github.com/bitwarden/server/releases/tag/v2026.5.0Fixvia CVE List
- github.com/bitwarden/server/commit/27ae3d5455f723975fac03819eaeba8710666bc4Fixvia CVE List
- vulncheck.com/advisories/bitwarden-server-authentication-bypass-via-sso-identifier-truncationAdvisoryvia CVE List
- sanjokkarki.com.np/blog/bitwarden-sso-externalid-truncationExploitvia CVE List
- github.com/bitwarden/server/pull/7501Referencevia CVE List