Auth bypass in Bitwarden Server
CVE-2026-43639
Bitwarden Server prior to v2026.4.0 contains a missing authorization vulnerability that allows a provider service user to add an arbitrary organization to their provider via `POST /providers/{providerId}/clients/existing`, resulting in tak…
Vulnerability class: Broken Access Control
EPSS: 0.000 (13.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.0 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H.
Affected products
- Bitwarden Server — versions 0
Weakness classification (CWE)
References
- disclosure@vulncheck.com (Exploit, technical-description, Third Party Advisory, exploit)
- disclosure@vulncheck.com (release-notes, Release Notes)
- disclosure@vulncheck.com (issue-tracking, Patch, Issue Tracking)
- disclosure@vulncheck.com (Patch, patch)
- disclosure@vulncheck.com (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-43639?
- CVE-2026-43639 is a high-severity vulnerability in Bitwarden Server, classified under Missing Authorization. CVSS score: 8.0/10. Published 2026-05-11.
- How severe is CVE-2026-43639?
- High severity. CVSS v3 base score is 8.0 out of 10.