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NVD / CVE Program· CNA VulnCheck

CVE-2026-43639: Bitwarden Server < 2026.4.0 Missing Authorization via Provider Clients

Noroxi assessment

Priority: Monitor (action score 35/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.59% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. Administrator privileges are required. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: bitwarden server 2026.4.0.

Low priority for now. Upgrade to bitwarden server 2026.4.0 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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).

HighCVSS 8.9 · v4.0—No exploit Fix available
Published
May 11, 2026
Updated
Nov 8, 2026
EPSS
0.5% · 48th percentile

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
35 / 40 · 8.9 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · VulnCheck
8.9
NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-43639

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
bitwardenserver

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • bitwarden serverbefore 2026.4.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.

  • bitwarden server

    • before 2026.4.0affected · semver

Same product

bitwarden: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-60104Bitwarden Server < 2026.6.0 Authorization Bypass via Admin Auth Request
    37Monitor
  • CVE-2026-43640Bitwarden Server < 2026.4.1 Authentication Bypass via SCIM API Key
    34Monitor
  • CVE-2020-15879Bitwarden Server 1.35.1 allows SSRF because it does not consider certain IPv6 addresses (ones beginning with fc, fd, fe, or ff, and the :: a
    31Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2019-19766Dec 12, 2019 · The Bitwarden server through 1.32.0 has a potentially unwanted KDF.
    30Monitor
  • ← EarlierCVE-2026-43638May 11, 2026 · Bitwarden Server < 2026.4.1 Missing Authorization via Organization Cipher Import
    21Monitor
  • Later →CVE-2026-57520Jun 25, 2026 · Bitwarden Server < 2026.5.0 Privilege Escalation via Bulk User Remove Endpoint
    28Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
bitwarden server2026.4.0Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-5752045 days apartBitwarden Server < 2026.5.0 Privilege Escalation via Bulk User Remove Endpoint
    28Monitor
  • CVE-2026-7195991 days apartBitwarden Server < 2026.7.2 Audit Log Injection via POST /collect
    27Monitor
  • CVE-2026-436380 days apartBitwarden Server < 2026.4.1 Missing Authorization via Organization Cipher Import
    21Monitor
  • CVE-2026-5752145 days apartBitwarden Server < 2026.5.0 Broken Access Control via PreviewInvoiceController
    21Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • Administrator privileges are required.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
High
Privileges required
High
User interaction
None
Scope
X

Weakness class (CWE)

CWE-862 · Missing Authorization

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records