CVE-2026-43639 PUBLISHED

Bitwarden Server < 2026.4.0 Missing Authorization via Provider Clients

Assigner: VulnCheck
Reserved: 01.05.2026 Published: 11.05.2026 Updated: 11.05.2026

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 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
CVSS Score: 8.9

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	High	Confidentiality	High
Attack Complexity	High	Integrity	High	Integrity	High
Attack Requirements	None	Availability	High	Availability	High
Privileges Required	High
User Interaction	None

CVSS 4.0

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
CVSS Score: 8

Attack Vector	Network	Scope	Changed
Attack Complexity	High	Confidentiality Impact	High
Privileges Required	High	Integrity Impact	High
User Interaction	None	Availability Impact	High

CVSS 3.1

Product Status

Vendor	bitwarden
Product	server
Versions	Default: affected affected from 0 to 2026.4.0 (excl.)

CVE-2026-43639 PUBLISHED

Bitwarden Server < 2026.4.0 Missing Authorization via Provider Clients

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Problem Types