CVE-2026-43639

Name: CVE-2026-43639
Creator: NVD / NIST
Published: 2026-05-11T18:16:36.97+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.9/10EPSS 0.60%

Last modified Jun 17, 2026

CVE-2026-43639 is a high-severity vulnerability rated 8.9/10 on the CVSS scale. 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).. EPSS estimates a 0.60% chance of exploitation in the next 30 days.

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).

Metrics

CVSS 3.1

9.1/10

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

CVSS 4.0

8.9/10

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/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

EPSS Probability

0.60%

44.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-862

Affected Software

Vendor	Product	Versions
Bitwarden	Server	< 2026.4.0

References

https://github.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0b1dPatch
https://github.com/bitwarden/server/pull/7372Issue Tracking, Patch
https://github.com/bitwarden/server/releases/tag/v2026.4.0Release Notes
https://sanjokkarki.com.np/blog/bitwarden-provider-takeoverExploit, Third Party Advisory
https://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-clientsThird Party Advisory

Timeline

Published: May 11, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-43639?

How severe is CVE-2026-43639?

CVE-2026-43639 has a CVSS score of 8.9/10 (HIGH severity). The EPSS model estimates a 0.60% probability of exploitation in the next 30 days.

How do I fix CVE-2026-43639?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-43639?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST