CVE-2026-27801Public exploitNetwork attack vector

Authenticated 2FA bypass via unpersisted attempt counter

Published Mar 4, 2026 · Updated Mar 4, 2026

Authentication bypass in Vaultwarden 1.34.3 and earlier allows remote authenticated users to perform 2FA-protected account actions. The validate_protected_action_otp function increments attempts only in a deserialized copy of pa.data, then saves the unchanged JSON so failed guesses remain at zero. Remote authenticated users can brute-force the six-digit email OTP to read the account API key or delete that account and owned organizations.

CVSS severity5.9
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Vaultwarden 1.34.3 and earlier allows remote authenticated users to perform 2FA-protected account actions. The validate_protected_action_otp function increments attempts only in a deserialized copy of pa.data, then saves the unchanged JSON so failed guesses remain at zero. Remote authenticated users can brute-force the six-digit email OTP to read the account API key or delete that account and owned organizations.

The record

CVE
CVE-2026-27801
Published
Mar 4, 2026
Updated
Mar 4, 2026
Vendor
Dani Garcia
Product
Vaultwarden
Classifications
CWE-307, T1110.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 4, 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=< 1.35.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Dani Garcia · Vaultwardenversion=< 1.35.0

Published CVSS scores

6.0GitHub, Inc.CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N
5.9NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
Privilegesauthenticated
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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