Quick answer
Direct answer
Risk scores
| CVSS metric | What it means |
|---|---|
| Attack vector (AV:N) | Network: reachable remotely |
| Attack complexity (AC:H) | High complexity |
| Attack requirements (AT:N) | No attack requirements |
| Privileges required (PR:H) | High privileges required |
| User interaction (UI:N) | No user interaction |
| Confidentiality (VC:H) | High confidentiality impact |
| Integrity (VI:H) | High integrity impact |
| Availability (VA:H) | High availability impact |
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
About Bitwarden Server
CVE-2026-43639 affects Bitwarden Server, a product from Bitwarden. Before acting, confirm where Bitwarden Server runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.
What the flaw is
In plain terms: 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).
The weakness class is Missing Authorization. The software does not check permissions before an action.
Based on its CVSS vector, the flaw can be reached over the network, needs some level of access, and needs no user interaction. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Affected versions and timeline
| Field | Detail |
|---|---|
| Product | Bitwarden Server |
| Affected versions | Server before 2026.4.0 |
| Published | May 11, 2026 |
| Last modified | Jul 14, 2026 |
| Added to CISA KEV | Not listed |
| Assigning CNA | disclosure@vulncheck.com |
How to detect it
- Inventory every instance of Bitwarden Server and record the running version against the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
- Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.
How to fix it
- Apply the fixed version of Bitwarden Server named in the vendor advisory.
- If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
- Rescan after the change to prove the exposure is gone, then close the ticket.
CTEM action plan
| CTEM stage | What to do for this CVE |
|---|---|
| Scope | Add every business service that depends on Bitwarden Server to the current CTEM cycle. |
| Discover | Find all instances, including shadow and cloud deployments, and record versions and exposure. |
| Prioritize | Rank using EPSS and CVSS together with asset exposure and business impact. |
| Validate | Confirm the flaw is reachable and exploitable in your environment and that compensating controls work. |
| Mobilize | Assign the fix to the asset owner with a due date matched to the priority, then verify closure. |
CWE References
- CWE-862: Missing Authorization More CVEs with this weakness
Technical References
Frequently asked questions
Related CVEs
Bitwarden Server before 2026.6.0 does not verify that the email in a POST /auth-requests/admin-request body belongs to the authenticated caller, allowing a low-privileged organization member to obtain another user's vault key and a victim-scoped access token by creating a Trusted Device Encryption authentication request, bound to an attacker-controlled public key, that is readable from an unauthenticated endpoint once approved resulting in disclosure of the victim's vault key and account takeover.
Bitwarden CLI 2026.4.0 from 2026-04-22T21:57Z to 2026-04-22T23:30Z, when obtained from npm, had embedded malicious code. This is related to a Checkmarx supply chain incident.
In Telecomm, there is a possible way to initiate an unauthorized phone call due to a permissions bypass. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.
A validation issue existed in the entitlement verification. This issue was addressed with improved validation of the process entitlement. This issue is fixed in macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7. A malicious app may be able to break out of its sandbox.
Missing authorization in Azure DNS allows an unauthorized attacker to elevate privileges over a network.
In NFC, there is a possible way to spoof an NFC event due to a missing permission check. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.
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