---
cve: "CVE-2026-43639"
severity: "HIGH"
cvss: 8.9
epss: "0.8%"
vendor: "Bitwarden"
kev: false
exploited: false
published: "2026-05-11 18:16:36"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-10-01T04:31:47+02:00"
---

# CVE-2026-43639

> 8.9 HIGH · 🧪 PoC

## Beschreibung

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).

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **poc**
  - Automatable: **no**
  - Technical Impact: **total**

## CVSS-Vektor

```
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
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Hoch | good |
| PR Privilegien | Hoch | good |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- a2efc7409cea90dfb9ffae309851935f57294f3f (Commit)
- 0918bfdda6f5eec391c69bd9074f6aef4eac0b1d (Commit)

## BSI-Hinweise (deutsch)

- [Bitwarden: Mehrere Schwachstellen](https://wid.cert-bund.de/portal/wid/sicherheitshinweis/WID-SEC-W-2026-1465)

## Referenzen

- <https://sanjokkarki.com.np/blog/bitwarden-provider-takeover>
- <https://github.com/bitwarden/server/releases/tag/v2026.4.0>
- <https://github.com/bitwarden/server/pull/7372>
- <https://github.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0b1d>
- <https://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-clients>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-43639) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_