Critical severity · published May 11, 2026
CVE-2026-43639
Bitwarden Server < 2026.4.0 Missing Authorization via Provider Clients
9.1
CVSS
0.6%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 48% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
SE
server · bitwarden
before 2026.4.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-43639
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-43639
Patch
https://github.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0b1d
Issue Tracking
https://github.com/bitwarden/server/pull/7372
Release Notes
https://github.com/bitwarden/server/releases/tag/v2026.4.0
Exploit
https://sanjokkarki.com.np/blog/bitwarden-provider-takeover
Third Party Advisory
https://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-clients
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