Missing Authorization Vulnerability in Bitwarden Server by Bitwarden
CVE-2026-43639

8.9HIGH

Key Information:

Vendor

Bitwarden

Status
Server
Vendor
CVE Published:
11 May 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-43639?

A vulnerability in Bitwarden Server versions prior to v2026.4.0 allows a provider service user to exploit a missing authorization mechanism. This flaw enables the user to add an arbitrary organization to their provider through a specific API endpoint, effectively taking over the target organization. This vulnerability is particularly relevant to cloud-hosted instances, as self-hosted installations are safeguarded from this risk due to restrictions imposed on the affected endpoint.

Affected Version(s)

server 0

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-43639 - Proof of Concept

References

https://sanjokkarki.com.np/blog/bitwarden-provider-takeover
technical-descriptionexploit
https://github.com/bitwarden/server/releases/tag/v2026.4.0
release-notes
https://github.com/bitwarden/server/pull/7372
issue-tracking

CVSS V4

Score:
8.9
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
High
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Sanjok Karki
.