CVE-2026-43639
Bitwarden Server < 2026.4.0 Missing Authorization via Provider Clients
Description
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).
INFO
Published Date :
May 11, 2026, 6:16 p.m.
Last Modified :
May 16, 2026, 3:04 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | MITRE-CVE | ||||
| CVSS 3.1 | CRITICAL | [email protected] | ||||
| CVSS 4.0 | HIGH | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update Bitwarden Server to version 2026.4.0 or later.
- Apply vendor patches and security updates immediately.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-43639.
| URL | Resource |
|---|---|
| https://github.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0b1d | Patch |
| https://github.com/bitwarden/server/pull/7372 | Issue Tracking Patch |
| https://github.com/bitwarden/server/releases/tag/v2026.4.0 | Release Notes |
| https://sanjokkarki.com.np/blog/bitwarden-provider-takeover | Exploit Third Party Advisory |
| https://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-clients | Third Party Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-43639 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-43639
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-43639 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-43639 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
May. 16, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H Added CPE Configuration OR *cpe:2.3:a:bitwarden:server:*:*:*:*:*:*:*:* versions up to (excluding) 2026.4.0 Added Reference Type VulnCheck: https://github.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0b1d Types: Patch Added Reference Type VulnCheck: https://github.com/bitwarden/server/pull/7372 Types: Issue Tracking, Patch Added Reference Type VulnCheck: https://github.com/bitwarden/server/releases/tag/v2026.4.0 Types: Release Notes Added Reference Type VulnCheck: https://sanjokkarki.com.np/blog/bitwarden-provider-takeover Types: Exploit, Third Party Advisory Added Reference Type VulnCheck: https://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-clients Types: Third Party Advisory -
New CVE Received by [email protected]
May. 11, 2026
Action Type Old Value New Value Added Description 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). Added CVSS V4.0 AV:N/AC:H/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CVSS V3.1 AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H Added CWE CWE-862 Added Reference https://github.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0b1d Added Reference https://github.com/bitwarden/server/pull/7372 Added Reference https://github.com/bitwarden/server/releases/tag/v2026.4.0 Added Reference https://sanjokkarki.com.np/blog/bitwarden-provider-takeover Added Reference https://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-clients