Vulnerability 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 Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Bitwarden | Server | < 2026.4.0 |
Related Weaknesses (CWE)
References
- https://github.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0Patch
- https://github.com/bitwarden/server/pull/7372Issue TrackingPatch
- https://github.com/bitwarden/server/releases/tag/v2026.4.0Release Notes
- https://sanjokkarki.com.np/blog/bitwarden-provider-takeoverExploitThird Party Advisory
- https://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-Third Party Advisory
FAQ
What is CVE-2026-43639?
CVE-2026-43639 is a vulnerability with a CVSS score of 8.0 (HIGH). 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/{provider...
How severe is CVE-2026-43639?
CVE-2026-43639 has been rated HIGH with a CVSS base score of 8.0/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-43639?
Check the references section above for vendor advisories and patch information. Affected products include: Bitwarden Server.