Is CVE-2026-43639 actively exploited?

No active exploitation of CVE-2026-43639 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-43639 be exploited remotely?

Yes. CVE-2026-43639 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-43639?

CVE-2026-43639 has a CVSS score of 9.1 (CRITICAL).

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CRITICAL

CVE-2026-43639

CWE-862Published: May 11, 2026· Updated: May 16, 2026

9.1

CVSS v3.1

EPSS:0.05%probability of exploitation in 30 daysPercentile:14.1th

Official 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).

NVD Source

Technical Analysis

CVE-2026-43639 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires high privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.1.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.