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 takeover of the…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.60%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 4.0
- 8.9 HIGHCVSS:4.0/AV:N/AC:H/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.60% probability · 47th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-862
- Affected
- bitwarden/server
- Source
- disclosure@vulncheck.com
References
- https://github.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0b1dPatch
- https://github.com/bitwarden/server/pull/7372Issue Tracking, Patch
- https://github.com/bitwarden/server/releases/tag/v2026.4.0Release Notes
- https://sanjokkarki.com.np/blog/bitwarden-provider-takeoverExploit, Third Party Advisory
- https://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-clientsThird Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.