CVE-2026-101878 json
Bitwarden Server 2025.6.0 < 2025.6.0 Authentication Bypass via SSO Identifier Truncation
published 2026-09-29 41 d ago modified 2026-11-08 24 h ago also EUVD-2026-88605
- cvss
- 7.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 17%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- bitwarden bitwarden server 2026.5.0
- github.com/bitwarden/server@27ae3d5 commit
- github.com/bitwarden/server#7501 pull request
- github.com/bitwarden/server/releases/tag/v2026.5.0 release
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- total
- Assessed
- 40 d ago
Exploit prediction
0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- sanjokkarki.com.np https://sanjokkarki.com.np/blog/bitwarden-sso-externalid-truncation referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 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 |
| CNA | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H |
| CNA | 4.0 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
Affected products
- bitwarden bitwarden server
Classification
- Weakness
-
- CWE-303 Incorrect Implementation of Authentication Algorithm
References
-
github.com
/bitwarden/server/pull/7501
issue-tracking, patch
-
github.com
/bitwarden/server/commit/27ae3d5455f723975fac03819eaeba8710666bc4
patch
-
sanjokkarki.com.np
/blog/bitwarden-sso-externalid-truncation
technical-description, exploit
-
github.com
/bitwarden/server/releases/tag/v2026.5.0
release-notes
-
vulncheck.com
/advisories/bitwarden-server-authentication-bypass-via-sso-identifier-truncation
third-party-advisory
Sources
- CVE List CVE-2026-101878
- NVD CVE-2026-101878
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.