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).
CVSS breakdown
CVSS 4.0
Attack Vector
Network
Attack Complexity
High
Attack Requirements
None
Privileges Required
High
User Interaction
None
Confidentiality (Vulnerable System)
High
Integrity (Vulnerable System)
High
Availability (Vulnerable System)
High
Confidentiality (Subsequent System)
High
Integrity (Subsequent System)
High
Availability (Subsequent System)
High
CVSS 3.1
Attack Vector
Network
Attack Complexity
High
Privileges Required
High
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High
Affected products
- bitwarden / server0 – 2026.4.0
References
- MISChttps://sanjokkarki.com.np/blog/bitwarden-provider-takeover
- PATCHhttps://github.com/bitwarden/server/releases/tag/v2026.4.0
- PATCHhttps://github.com/bitwarden/server/pull/7372
- PATCHhttps://github.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0b1d
- VENDOR_ADVISORYhttps://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-clients