CVE-2026-43639: Bitwarden Server prior to v2026.4.0 contains a missing authorization vulnerability that allows a provider serv

Q: How do I fix CVE-2026-43639?

server: upgrade to 2026.4.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-43639 being exploited?

CVE-2026-43639 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-43639 affect?

CVE-2026-43639 affects server. Severity is high (CVSS 8.0). 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 take

Q: How urgent is CVE-2026-43639?

Priority 45/100. High severity; Public exploit reference

This month

HIGH 8.0UPGRADE

CVE-2026-43639 is a high-severity flaw (CVSS 8.0) affecting server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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).

Why this priority

High severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	8.0 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	High
User interaction	None
EPSS exploit chance	0.6% (top 52%)
CISA exploited list	No
Weakness	CWE-862
Published	2026-05-11
Last modified	2026-10-26

Publisher (CNA): VulnCheck · Vendor: bitwarden

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-11 18:16 UTCPublished CVE record published
2026-10-26 18:10 UTCUpdated Record last modified

bitwarden server UPGRADE

Affected: < 2026.4.0

Fixed in: 2026.4.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy server || rpm -q server || server --version

2. UPGRADE to 2026.4.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade server

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade server

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-43639?

server: upgrade to 2026.4.0. Exact commands for each OS are on this page.

Is CVE-2026-43639 being exploited?

CVE-2026-43639 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-43639 affect?

CVE-2026-43639 affects server. Severity is high (CVSS 8.0). 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 take

How urgent is CVE-2026-43639?

Priority 45/100. High severity; Public exploit reference

Related CVEs

CVE-2026-6408 LOW 2.7 UPGRADE Tanium addressed an information disclosure vulnerability in Tanium Server.
CVE-2026-43640 HIGH 8.1 UPGRADE Bitwarden Server prior to v2026.4.1 does not require master-password re-authentication when retrieving or rota
CVE-2026-43638 MEDIUM 5.4 UPGRADE Bitwarden Server prior to v2026.4.1 contains a missing authorization vulnerability that allows any authenticat
CVE-2026-57520 HIGH 7.1 UPGRADE Bitwarden Server before 2026.5.0 contains a privilege escalation vulnerability that allows authenticated Custo
CVE-2026-57521 MEDIUM 4.3 UPGRADE Bitwarden Server before 2026.5.0 contains a broken access control vulnerability that allows any authenticated

References

← Back to latest CVEs