CVE-2026-43639

Bitwarden Server < 2026.4.0 Missing Authorization via Provider Clients

CVSS 8.9 HIGHEPSS 0.6%CWE-862

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:4.0/AV:N/AC:H/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Affected products

bitwarden · server

public PoCs found — 1

cve_referencesanjokkarki.com.np/blog/bitwarden-provider-takeoverunverified

⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.

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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