Missing Authorization in Bitwarden Server Allows Unauthorized Cipher Writing
CVE-2026-43638

5.3MEDIUM

Key Information:

Vendor

Bitwarden

Status
Server
Vendor
CVE Published:
11 May 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-43638?

A vulnerability in Bitwarden Server prior to v2026.4.1 allows any authenticated user to exploit a missing authorization check. By sending an empty collections array in a request to POST /ciphers/import-organization, attackers can bypass the server-side permission validation. This flaw enables unauthorized users to write ciphers into any arbitrary organization, potentially compromising sensitive data and organizational structures within Bitwarden. It's crucial to upgrade to the latest version to mitigate this risk.

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-2026-43638 - Proof of Concept

References

https://sanjokkarki.com.np/blog/bitwarden-import-org-bypass
technical-descriptionexploit
https://github.com/bitwarden/server/releases/tag/v2026.4.1
release-notes
https://github.com/bitwarden/server/pull/7394
issue-tracking

CVSS V4

Score:
5.3
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
Low
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Sanjok Karki
.