CVE-2026-43639

Bitwarden Server < 2026.4.0 Missing Authorization via Provider Clients

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).

Affected

bitwarden · server

CVSS v4.0 VULNCHECK

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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1 NVD

9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

CVSS v3.1 VULNCHECK

8.0 HIGHCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

EPSS

0.84% chance of exploitation in the next 30 days, 57th percentile

Published

2026-05-11

Updated

2026-07-14

Proof-of-concept exploits (1)

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

Security advisories

• https://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-…
• bitwarden/server/pull/7372

References

• CVE Record
• NVD entry