CVE-2026-43639Public exploitNetwork attack vector

Cloud organization takeover via unchecked ownership

Published May 11, 2026 · Updated May 11, 2026

Missing authorization in Bitwarden Server before 2026.4.0 allows remote authenticated users to take over cloud organizations. AddExistingOrganizationAsync loads an arbitrary organization ID without verifying that the provider user owns the target. Exploitation requires a vetted cloud provider account and the target organization GUID; self-hosted installations cannot reach the route.

CVSS severity8.9
High
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing authorization in Bitwarden Server before 2026.4.0 allows remote authenticated users to take over cloud organizations. AddExistingOrganizationAsync loads an arbitrary organization ID without verifying that the provider user owns the target. Exploitation requires a vetted cloud provider account and the target organization GUID; self-hosted installations cannot reach the route.

The record

CVE
CVE-2026-43639
Published
May 11, 2026
Updated
May 11, 2026
Vendor
Bitwarden
Product
Bitwarden Server
Classifications
CWE-862, T1098.003
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 11, 2026CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <2026.4.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Bitwarden · Bitwarden Serverversion=0 <2026.4.0

Published CVSS scores

8.9VulnCheckCVSS:4.0/AV:N/AC:H/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
9.1NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
8.0VulnCheckCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-862Missing Authorization
T1098.003Account Manipulation: Additional Cloud Roles

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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