CVE-2026-101878— Bitwarden Server 2025.6.0 < 2025.6.0 Authentication Bypass via SSO Identifier Truncation
Quick assessment
Affected
bitwarden bitwarden server
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
Bitwarden 服务器 2025.6.0 至 2026.5.0（不含 2026.5.0）版本中， 存储过程将 参数声明为 ，而其所查询的数据库列实际存储类型为 。这一不匹配导致在 SQL Server 部署环境下，SSO（单点登录）身份标识会被静默截断为前 50 个字符。攻击者可利用此缺陷，通过构造其身份提供者的标识符以另一位组织成员的完整 50 字符标识符作为前缀，从而冒充该成员进行认证，并获取仅限受害者范围访问的令牌。
Possible ATT&CK Techniques 1 AI
T1078 · Valid AccountsAffected Version Matrix 1
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| bitwarden | bitwarden server | 2025.6.0< 2026.5.0 |
affected |
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I. Basic Information for CVE-2026-101878
Vulnerability Information
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Vulnerability Title
Bitwarden Server 2025.6.0 < 2025.6.0 Authentication Bypass via SSO Identifier Truncation
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
认证算法的不正确实现
Source: CVE Program / CVE List V5
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| bitwarden | bitwarden server | 2025.6.0 ~ 2026.5.0 | - |
|
II. Public POCs for CVE-2026-101878
| # | POC Description | Source Link | Shenlong Link |
|---|
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Patches & Fixes for CVE-2026-101878 (2)
Security Blog Posts for CVE-2026-101878 (1)
Vendor Pages for CVE-2026-101878 (1)
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🔗 Release Version 2026.5.0 · bitwarden/server · GitHub release-notes
Other References for CVE-2026-101878 (1)
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