CVE-2026-101878

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.

CVSS 4.0

7.7CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS 3.1

7.5CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

0.3% chance of exploitation in the next 30 days; higher than 17% of CVEs (scores of 2026-10-25)

CWE

CWE-303

Published

2026-09-29

Modified

2026-09-30

Record from

the NVD, synced 2026-10-19

References

• https://github.com/bitwarden/server/commit/27ae3d5455f723975fac03819eaeba8710666bc4
• https://github.com/bitwarden/server/pull/7501
• https://github.com/bitwarden/server/releases/tag/v2026.5.0
• https://sanjokkarki.com.np/blog/bitwarden-sso-externalid-truncation
• https://www.vulncheck.com/advisories/bitwarden-server-authentication-bypass-via-sso-identifier-truncation

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