CVE-2026-43639

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).

References

• https://github.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0b1d
• https://github.com/bitwarden/server/pull/7372
• https://github.com/bitwarden/server/releases/tag/v2026.4.0
• https://sanjokkarki.com.np/blog/bitwarden-provider-takeover
• https://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-clients