VulnerabilityPublished 11 May 2026

CVE-2026-43914: dani-garcia vaultwarden · Improper Restriction of Excessive Authentication Attempts

Affects dani-garcia vaultwardenSource CVE Database V5

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Not known to be exploited · CVSS 7.3 High : upgrade to 1.35.4 soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

7.3High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 21% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.35.4

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 11 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
Public exploit code: GitHub proofs of concept
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade vaultwarden and dani-garcia/vaultwarden to 1.35.4.

Affected software

Product	Affected	Fixed in
dani-garciavaultwarden	Affected <1.35.4	Fixed in 1.35.4
GitHubdani-garcia/vaultwarden`pkg:github/dani-garcia/vaultwarden`Other threats	Affected <1.35.4	Fixed in 1.35.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade Vaultwarden to version 1.35.4 or later, where this vulnerability is fixed. Until upgraded, be aware that brute-force protections can be bypassed via the email 2FA endpoint.

Description

Vaultwarden versions prior to 1.35.4 contain a vulnerability that allows attackers to bypass brute-force login protections when email two-factor authentication (2FA) is enabled. The vulnerability arises because the 2FA email function send_email_login acts as an oracle to verify username-password correctness without rate limiting. This flaw enables brute-force password attempts even against accounts without email 2FA configured. The issue is fixed in version 1.35.4. The CVSS score is 7.3, indicating a high severity vulnerability.

Impact

An attacker can perform brute-force password attacks against Vaultwarden user accounts by abusing the unprotected 2FA email login endpoint. This can lead to unauthorized access, compromising confidentiality, integrity, and availability of user data. The vulnerability affects all users on vulnerable versions regardless of whether they have email 2FA enabled. No known exploits in the wild have been reported as of the published date.

Summary

Vaultwarden, a Bitwarden-compatible server written in Rust, has a vulnerability (CVE-2026-43914) affecting versions before 1.35.4. The vulnerability involves improper restriction of excessive authentication attempts (CWE-307). Specifically, the send_email_login API endpoint used for email 2FA can be abused as an oracle to confirm valid username-password pairs without rate limiting, enabling brute-force attacks. This bypass affects all users, including those without email 2FA enabled. The vulnerability is resolved in Vaultwarden version 1.35.4.

CWE-307Improper Restriction of Excessive Authentication Attempts (opens in a new tab)
Base weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame.
Architecture and Design
Common protection mechanisms include: Disconnecting the user after a small number of failed attempts; Implementing a timeout; Locking out a targeted account; Requiring a computational task on the user's part.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
Authentication (opens in a new tab)
Transport Layer Protection (opens in a new tab)
TLS Cipher String (opens in a new tab)
OWASP ASVS 4.0.3
V2.2.1 (opens in a new tab)
V2.8.5 (opens in a new tab)
V2.8.4 (opens in a new tab)
Attack patterns
Dictionary-based Password Attack (opens in a new tab)
Password Brute Forcing (opens in a new tab)
Password Spraying (opens in a new tab)
Credential Stuffing (opens in a new tab)
Use of Known Kerberos Credentials (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 19 May 2026, 11:05 UTC

Public exploits and detectionGitHub proofs of concept

WeaknessesCWE-307

Technical details

References

Community reviews

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