CVE-2026-43914: CWE-307: Improper Restriction of Excessive Authentication Attempts in dani-garcia vaultwarden
Vaultwarden versions prior to 1. 35. 4 contain a vulnerability that allows an attacker to bypass brute-force login protections when email two-factor authentication (2FA) is enabled. The vulnerability exists in the send_email_login function, which can be used as an oracle to verify username-password combinations without rate limiting. This flaw enables brute-force attacks even against accounts without email 2FA configured. The issue is fixed in version 1. 35. 4.
AI Analysis
Technical Summary
CVE-2026-43914 is a vulnerability in Vaultwarden (a Bitwarden-compatible server) before version 1.35.4. The flaw involves improper restriction of excessive authentication attempts (CWE-307) via the /api/two-factor/send-email-login endpoint. When email 2FA is enabled, this endpoint can be abused to confirm valid username-password pairs without triggering rate limiting, effectively bypassing brute-force protections. This vulnerability affects all users regardless of whether they have email 2FA configured. The vulnerability has a CVSS 3.1 score of 7.3 (high severity) and was fixed in Vaultwarden 1.35.4.
Potential Impact
An attacker can perform brute-force password guessing attacks without rate limiting by abusing the email 2FA login endpoint, potentially leading to unauthorized access to user accounts. The vulnerability compromises confidentiality, integrity, and availability to a limited extent as indicated by the CVSS vector. There are no known exploits in the wild as of the published date.
Mitigation Recommendations
Upgrade Vaultwarden to version 1.35.4 or later, where this vulnerability is fixed. No other mitigations are documented or recommended. Patch status is not explicitly stated in the vendor advisory, but the fix is included in version 1.35.4.
CVE-2026-43914: CWE-307: Improper Restriction of Excessive Authentication Attempts in dani-garcia vaultwarden
Description
Vaultwarden versions prior to 1. 35. 4 contain a vulnerability that allows an attacker to bypass brute-force login protections when email two-factor authentication (2FA) is enabled. The vulnerability exists in the send_email_login function, which can be used as an oracle to verify username-password combinations without rate limiting. This flaw enables brute-force attacks even against accounts without email 2FA configured. The issue is fixed in version 1. 35. 4.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-43914 is a vulnerability in Vaultwarden (a Bitwarden-compatible server) before version 1.35.4. The flaw involves improper restriction of excessive authentication attempts (CWE-307) via the /api/two-factor/send-email-login endpoint. When email 2FA is enabled, this endpoint can be abused to confirm valid username-password pairs without triggering rate limiting, effectively bypassing brute-force protections. This vulnerability affects all users regardless of whether they have email 2FA configured. The vulnerability has a CVSS 3.1 score of 7.3 (high severity) and was fixed in Vaultwarden 1.35.4.
Potential Impact
An attacker can perform brute-force password guessing attacks without rate limiting by abusing the email 2FA login endpoint, potentially leading to unauthorized access to user accounts. The vulnerability compromises confidentiality, integrity, and availability to a limited extent as indicated by the CVSS vector. There are no known exploits in the wild as of the published date.
Mitigation Recommendations
Upgrade Vaultwarden to version 1.35.4 or later, where this vulnerability is fixed. No other mitigations are documented or recommended. Patch status is not explicitly stated in the vendor advisory, but the fix is included in version 1.35.4.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-04T16:11:33.086Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a028743cbff5d86108b507a
Added to database: 5/12/2026, 1:49:55 AM
Last enriched: 5/12/2026, 1:52:17 AM
Last updated: 5/12/2026, 3:48:43 AM
Views: 2
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