CVE-2026-43639

high

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://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-clients

https://sanjokkarki.com.np/blog/bitwarden-provider-takeover

https://github.com/bitwarden/server/releases/tag/v2026.4.0

https://github.com/bitwarden/server/pull/7372

https://github.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0b1d

Details

Source: Mitre, NVD

Published: 2026-05-11

Updated: 2026-05-16

Risk Information

CVSS v2

Base Score: 8.3

Vector: CVSS2#AV:N/AC:L/Au:M/C:C/I:C/A:C

Severity: High

CVSS v3

Base Score: 9.1

Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Severity: Critical

CVSS v4

Base Score: 8.9

Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Severity: High

EPSS

EPSS: 0.00046