# CVE-2026-101878: Bitwarden Server 2025.6.0 < 2025.6.0 Authentication Bypass via SSO Identifier Truncation

> CVE-2026-101878: Bitwarden Server 2025.6.0 < 2025.6.0 Authentication Bypass via SSO Identifier Truncation. CVSS 7.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-101878
Last updated: 2026-10-01T19:19:18Z

- Published: 2026-09-29 01:58 UTC · Updated: 2026-10-01 19:19 UTC · Assigner: VulnCheck
- CVSS: 7.5 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS: 0.26%, 17th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-303

## 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.

## Affected vendors and products

- bitwarden: bitwarden server

## Tracked companies

- [Bitwarden](https://rewindex.com/company/bitwarden.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-101878)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-101878)
- [https://github.com/bitwarden/server/commit/27ae3d5455f723975fac03819eaeba8710666bc4](https://github.com/bitwarden/server/commit/27ae3d5455f723975fac03819eaeba8710666bc4)
- [https://github.com/bitwarden/server/pull/7501](https://github.com/bitwarden/server/pull/7501)
- [https://github.com/bitwarden/server/releases/tag/v2026.5.0](https://github.com/bitwarden/server/releases/tag/v2026.5.0)
- [https://sanjokkarki.com.np/blog/bitwarden-sso-externalid-truncation](https://sanjokkarki.com.np/blog/bitwarden-sso-externalid-truncation)
- [https://www.vulncheck.com/advisories/bitwarden-server-authentication-bypass-via-sso-identifier-truncation](https://www.vulncheck.com/advisories/bitwarden-server-authentication-bypass-via-sso-identifier-truncation)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-101878 · Markdown: https://rewindex.com/cve/CVE-2026-101878.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-101878 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:11:26.133Z