CVE-2026-43639: Missing Authorization in bitwarden server
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).
AI Analysis
Technical Summary
Bitwarden Server before version 2026.4.0 contains a missing authorization vulnerability in the POST /providers/{providerId}/clients/existing endpoint. This flaw permits a provider service user to add any organization to their provider, which can result in the takeover of that organization. The vulnerability is limited to the cloud-hosted Bitwarden service since the endpoint is restricted to non-self-hosted environments. There is no vendor advisory or patch available at this time, and the vulnerability has a CVSS 4.0 score of 8.9, indicating high severity.
Potential Impact
An attacker with provider service user privileges can exploit this vulnerability to add arbitrary organizations to their provider, leading to potential takeover of those organizations. This could compromise organizational data and control within the affected Bitwarden cloud service. Self-hosted Bitwarden installations are not affected due to endpoint restrictions.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no official fix or remediation level is provided, organizations using the affected cloud-hosted Bitwarden Server versions should monitor vendor communications for updates. Self-hosted deployments are not impacted by this vulnerability.
CVE-2026-43639: Missing Authorization in bitwarden server
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 v4.0
Score 8.9high
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Bitwarden Server before version 2026.4.0 contains a missing authorization vulnerability in the POST /providers/{providerId}/clients/existing endpoint. This flaw permits a provider service user to add any organization to their provider, which can result in the takeover of that organization. The vulnerability is limited to the cloud-hosted Bitwarden service since the endpoint is restricted to non-self-hosted environments. There is no vendor advisory or patch available at this time, and the vulnerability has a CVSS 4.0 score of 8.9, indicating high severity.
Potential Impact
An attacker with provider service user privileges can exploit this vulnerability to add arbitrary organizations to their provider, leading to potential takeover of those organizations. This could compromise organizational data and control within the affected Bitwarden cloud service. Self-hosted Bitwarden installations are not affected due to endpoint restrictions.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no official fix or remediation level is provided, organizations using the affected cloud-hosted Bitwarden Server versions should monitor vendor communications for updates. Self-hosted deployments are not impacted by this vulnerability.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-05-01T18:22:45.642Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a021aa7cbff5d861043051d
Added to database: 05/11/2026, 18:06:31 UTC
Last enriched: 07/15/2026, 10:33:16 UTC
Last updated: 07/31/2026, 19:22:59 UTC
Views: 164
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