by Kastro
Paper/Archive/CVE-2026-43639

CVE-2026-43639

bitwarden server — Bitwarden Server < 2026.4.0 Missing Authorization via Provider Clients

EPSS 0.6%public exploitCVSS 9.1
critical.is priorityof 100
47
CVSS 9.1 (NVD)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 48.4.484 × 209.7Exploit: SSVC poc+1010.0SSVC exploitation: poc+100.0
Description · from the CVE record

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).

Affected

ProductAffectedFixed inSource
server< 2026.4.02026.4.0CNA

Scores by source

NVD9.1CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
VulnCheck (CNA)8.9CVSS:4.0/AV:N/AC:H/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
VulnCheck (CNA)8.0CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
CISA ADPSSVCExploitation: poc · Automatable: no · Technical impact: total

References

exploitsanjokkarki.com.np/blog/bitwarden-provider-takeoverrefgithub.com/bitwarden/server/releases/tag/v2026.4.0refgithub.com/bitwarden/server/pull/7372patchgithub.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0b1dwriteupvulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-clients