CVE-2026-43639 HIGH

CVE-2026-43639: Bitwarden Server < 2026.4.0 Missing Authorization via Provider Clients

Vendor Bitwarden

Product server

Weakness CWE-862 · Missing authorization

Published May 11, 2026

Last update May 11, 2026

View on NVD All CVEs

CVSS base score

8.9/10

Attack vector Network

Attack complexity High

Privileges required High

User interaction None

Confidentiality —

Integrity —

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

What the vulnerability does

01Description

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).

Key dates

02Disclosure timeline

May 11, 2026 CVE published

May 11, 2026 Record updated

External resources

03References

NVD — National Vulnerability Database https://nvd.nist.gov/vuln/detail/CVE-2026-43639 CWE — Common Weakness Enumeration https://cwe.mitre.org/data/definitions/862.html

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04Related CVE

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