Description
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 takeover of the target organization; self-hosted installations are unaffected as this endpoint is restricted to Cloud via SelfHosted(NotSelfHostedOnly = true).
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| bitwarden | server | < 2026.4.0 | 2026.4.0 |
Advisories 1
- WID-SEC-2026-1465 Bitwarden: Mehrere Schwachstellen BSI CERT-Bund (WID) · May 11, 2026
References
- https://sanjokkarki.com.np/blog/bitwarden-provider-takeover technical-description exploit
- server 2026.4.0 Release Notes release-notes
- https://github.com/bitwarden/server/pull/7372 issue-tracking patch
- https://github.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0b1d patch
- https://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-clients third-party-advisory