Cyber Posture

CVE-2026-43914

High

Published: 11 May 2026

Published
11 May 2026
Modified
12 May 2026
KEV Added
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Patch
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CVSS Score 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
EPSS Score 0.0004 10.7th percentile
Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-43914 is a high-severity Improper Restriction of Excessive Authentication Attempts (CWE-307) vulnerability. Its CVSS base score is 7.3 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Brute Force (T1110); ranked at the 10.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

Threat & Defense at a Glance

What attackers do: exploitation maps to Brute Force (T1110) and 1 other technique.
Threat & Defense Details

Likely Mitigating ControlsAI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

AC-7 Unsuccessful Logon Attempts
addresses: CWE-307

This control directly enforces limits on consecutive invalid logon attempts and automatic response (e.g., lockout) to prevent brute-force exploitation of authentication mechanisms.

IA-10 Adaptive Authentication
addresses: CWE-307

Specific conditions can include excessive failed attempts, triggering stronger authentication that restricts brute-force exploitation.

MITRE ATT&CK Enterprise TechniquesAI

T1110 Brute Force Credential Access
Adversaries may use brute force techniques to gain access to accounts when passwords are unknown or when password hashes are obtained.
attack.mitre.org →
T1110.001 Password Guessing Credential Access
Adversaries with no prior knowledge of legitimate credentials within the system or environment may guess passwords to attempt access to accounts.
attack.mitre.org →
Why these techniques?

Vulnerability directly bypasses rate-limiting on auth attempts via 2FA oracle endpoint, enabling password guessing/brute force (CWE-307).

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

Vaultwarden is a Bitwarden-compatible server written in Rust. Prior to 1.35.4, there is a security vulnerability in Vaultwarden that allows bypassing the login brute-force protection if email 2fa is enabled. If email 2fa is enabled, the unprotected 2fa-function send_email_login (email.rs,…

more

api endpoint /api/two-factor/send-email-login) also acts as an oracle determining whether a username-password combination is correct. An attacker can abuse that endpoint to brute-force passwords without rate-limiting. This works even for users who don't have email 2fa configured. This vulnerability is fixed in 1.35.4.

Deeper analysisAI

Automated synthesis unavailable for this CVE.

Details

CWE(s)
CWE-307

References