Vulnerability in Bitwarden Server
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.
Published .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/bitwarden/server/commit/27ae3d5455f723975fac03819eaeba8710666bc4 (patch)
- github.com/bitwarden/server/pull/7501 (issue-tracking)
- github.com/bitwarden/server/releases/tag/v2026.5.0 (release-notes)
- sanjokkarki.com.np/blog/bitwarden-sso-externalid-truncation (technical-description, exploit)
- www.vulncheck.com/advisories/bitwarden-server-authentication-bypass-via-sso-ide… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-101878?
- CVE-2026-101878 is a high-severity vulnerability in Bitwarden Server, classified under Incorrect Implementation of Authentication Algorithm. CVSS score: 7.5/10. Published 2026-09-29.
- How severe is CVE-2026-101878?
- High severity. CVSS v3 base score is 7.5 out of 10.