Cyber Resilience

CVE-2026-43640

HighPublic PoC

Published: 11 May 2026

Published
11 May 2026
Modified
16 May 2026
KEV Added
—
Patch
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CVSS Score v4 8.6 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/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 Score 0.0050 39.3th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-43640 is a high-severity Incorrect Implementation of Authentication Algorithm (CWE-303) vulnerability in Bitwarden Server. Its CVSS base score is 8.6 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Steal Application Access Token (T1528); ranked at the 39.3th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

OWASP Top 10 for Web (2025)

A07:2025 Authentication Failures

EU & UK References

Vulnerability details

Bitwarden Server prior to v2026.4.1 does not require master-password re-authentication when retrieving or rotating an organization's SCIM API key, allowing an authenticated user with SCIM management privileges to obtain the key using only a valid session.

CWE(s)
CWE-303

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1528 Steal Application Access Token Credential Access
Adversaries can steal application access tokens as a means of acquiring credentials to access remote systems and resources.
attack.mitre.org →
Why these techniques?

Missing re-authentication allows an authenticated session to directly retrieve/rotate the SCIM API key (an application access token), enabling T1528.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-43639Same product: Bitwarden Server
CVE-2025-13390Shared CWE-303
CVE-2026-41103Shared CWE-303
CVE-2025-4676Shared CWE-303
CVE-2025-57808Shared CWE-303
CVE-2025-14510Shared CWE-303
CVE-2026-0073Shared CWE-303
CVE-2025-21311Shared CWE-303
CVE-2025-66489Shared CWE-303
CVE-2026-28446Shared CWE-303

Affected Assets

bitwarden
server
≤ 2026.4.1

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References