CVE-2026-43639

EUVD-2026-29170
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).
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
VulnCheckCNA
8 HIGH
NETWORK
HIGH
HIGH
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 48.74%
Affected Products (NVD)
VendorProductVersion
bitwardenserver
𝑥
< 2026.4.0
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources (CNA/ADP records, vendor advisories, Enginsight analysis).
VendorProductVersionSource
bitwardenbitwarden
𝑥
< 2026.4.0
CNA
Common Weakness Enumeration
References
https://github.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0b1d
https://github.com/bitwarden/server/pull/7372
https://github.com/bitwarden/server/releases/tag/v2026.4.0
https://sanjokkarki.com.np/blog/bitwarden-provider-takeover
https://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-clients