Home/CVE/Bitwarden Server prior to v2026.4.0 contains a missing authorization vulnerability that allows a provider service user t
CVE

CVE-2026-43639

Bitwarden Server prior to v2026.4.0 contains a missing authorization vulnerability that allows a provider service user t

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).

HIGH · CVSS 8 EPSS 0.00043
Act now
  • Public exploit or PoC is available
  • CVSS base score ≥ 7.0
Sigma rules5 YARA rules0
⬡

Weakness Classification

CWE-862Missing Authorization
▤

Affected Products & Versions

1
bitwarden server< 2026.4.0
⚠

Public Exploits & PoCs

1
pocsanjokkarki.com.np · bitwarden-provider-takeoversanjokkarki.com.np
◈

Sigma Hunt Rules

5
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
producthighPotential Server Side Template Injection In Velocity
producthighRemote Server Service Abuse for Lateral Movement
producthighRemote Server Service Abuse
producthighSuspicious Child Process Of SQL Server
producthighSuspicious Process By Web Server Process
▣

Scoring & Timeline

8
HIGH · CVSS v3.1 · disclosure@vulncheck.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD11 May 2026 · 06:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
poc
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
🔗

References & Sources

4
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0b1dPatch
https://github.com/bitwarden/server/pull/7372Issue TrackingPatch
https://github.com/bitwarden/server/releases/tag/v2026.4.0Release Notes
https://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-clientsThird Party Advisory
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