CVE-2026-43914Public exploitNetwork attack vector

Unauthenticated password brute force via unthrottled 2FA oracle

Published May 11, 2026 · Updated May 11, 2026

Authentication-rate-limit bypass in Vaultwarden before 1.35.4 allows remote attackers to brute-force account passwords over HTTP. The send_email_login handler at /api/two-factor/send-email-login validates credentials but omits check_limit_login, and distinct responses expose whether each password guess is correct. Email 2FA must be enabled on the instance, but every account is exposed even when the targeted user has not enabled email 2FA.

CVSS severity7.3
High
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication-rate-limit bypass in Vaultwarden before 1.35.4 allows remote attackers to brute-force account passwords over HTTP. The send_email_login handler at /api/two-factor/send-email-login validates credentials but omits check_limit_login, and distinct responses expose whether each password guess is correct. Email 2FA must be enabled on the instance, but every account is exposed even when the targeted user has not enabled email 2FA.

The record

CVE
CVE-2026-43914
Published
May 11, 2026
Updated
May 11, 2026
Vendor
Dani Garcia
Product
Vaultwarden
Classifications
CWE-307, T1110.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 11, 2026CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.35.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Dani Garcia · Vaultwardenversion=< 1.35.4

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-307Improper Restriction of Excessive Authentication Attempts
T1110.001Password Guessing

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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