CVE-2026-101878CWE-303

CVE-2026-101878

High · published September 29, 2026

CVSS v3.1
7.5
EPSS
0%
Percentile
16.6
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
7.7 · 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
EPSS
0.00258 · 16.6th percentile
Weakness
CWE-303 · Incorrect Implementation of Authentication Algorithm
Published
2026-09-29T06:16Z
References (5)
https://github.com/bitwarden/server/commit/27ae3d5455f723975fac03819eaeba8710666bc4 · [email protected]https://github.com/bitwarden/server/pull/7501 · [email protected]https://github.com/bitwarden/server/releases/tag/v2026.5.0 · [email protected]https://sanjokkarki.com.np/blog/bitwarden-sso-externalid-truncation · [email protected]https://www.vulncheck.com/advisories/bitwarden-server-authentication-bypass-via-sso-identifier-truncation · [email protected]
EPSS history
Timeline
  • 30 SEP 03:24Z
    EPSS moved — → 0%
    epss
  • 29 SEP 01:58Z
    Bitwarden Server 2025.6.0 < 2025.6.0 Authentication Bypass via SSO Identifier Truncation
    cvelistv5