VulnerabilityPublished 7 Jul 2026Updated 20 Jul 2026

CVE-2026-53516: Better Auth has an account takeover issue via OAuth auto-link to unverified pre-registered email

Affects better-authSource GCVE Database

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Not known to be exploited · CVSS 8.3 High : upgrade to 1.6.11 soon.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 3.1 base score

8.3High

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 1.6.11

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: High
Integrity: High
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: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
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: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to 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 7 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
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), the Metasploit, Exploit-DB and nuclei-templates index as of 29 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 better-auth to 1.6.11.

Affected software

Product	Affected	Fixed in
npmbetter-auth	Affected <1.6.11	Fixed in 1.6.11

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

AI-suggested

A fix is available in better-auth version 1.6.11 and later, which adds a local email verification check before implicit OAuth account linking. Users should upgrade to version 1.6.11 or later. If immediate upgrade is not possible, developers can mitigate by disabling implicit linking via account.accountLinking.disableImplicitLinking: true, forcing explicit linking through authenticated endpoints, or by disabling account linking entirely with account.accountLinking.enabled: false, though this breaks multi-login-method UX. The requireEmailVerification setting alone does not mitigate this vulnerability.

Description

A vulnerability in better-auth versions prior to 1.6.11 allows an attacker to perform account takeover via OAuth auto-linking to an unverified pre-registered email. The flaw arises because the OAuth callback implicitly links accounts based only on the OAuth provider's email verification claim, ignoring the local user's email verification status. This enables an attacker to pre-register a victim's email with an unverified password login and later have the victim's OAuth login linked to the attacker's account, granting persistent access. The issue bypasses the requireEmailVerification setting and affects all OAuth and SSO sign-in flows calling handleOAuthUserInfo. The vulnerability is fixed in better-auth 1.6.11 by requiring the local email to be verified before implicit linking.

Impact

This vulnerability enables account takeover through pre-account hijacking by allowing an attacker to bind a victim's OAuth identity to the attacker's pre-registered password login account, granting persistent access. It bypasses the requireEmailVerification setting by promoting the attacker's unverified email to verified after linking. The issue affects all OAuth and SSO sign-in flows using better-auth's handleOAuthUserInfo, potentially compromising user accounts and authentication integrity.

Summary

The vulnerability in better-auth before version 1.6.11 involves the OAuth callback's auto-linking mechanism in handleOAuthUserInfo, which implicitly links an OAuth identity to a local user account if the OAuth provider asserts email_verified: true, without checking the local user's emailVerified flag. An attacker can pre-register a victim's email with emailVerified: false and later cause the victim's OAuth login to link to the attacker's account, effectively hijacking the victim's account by combining password and OAuth logins. The local emailVerified flag is then promoted to true post-link, defeating mitigations like requireEmailVerification: true. The fix adds a local-side check to reject implicit linking if the local email is unverified. Workarounds include disabling implicit linking or disabling account linking entirely, though these impact user experience. The vulnerability affects all OAuth and SSO providers integrated with better-auth that call handleOAuthUserInfo.

CWE-287Improper Authentication (opens in a new tab)
Class weaknessLikelihood of exploit: HighOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design · Libraries or Frameworks
Use an authentication framework or library such as the OWASP ESAPI Authentication feature.
OWASP Cheat Sheets
OWASP Authentication (opens in a new tab)
OWASP ASVS 4.0.3
V2.8.5 (opens in a new tab)
V2.8.4 (opens in a new tab)
V9.2.3 (opens in a new tab)
Attack patterns
Fake the Source of Data (opens in a new tab)
Utilizing REST's Trust in the System Resource to Obtain Sensitive Data (opens in a new tab)
Session Hijacking (opens in a new tab)
Token Impersonation (opens in a new tab)
Upload a Web Shell to a Web Server (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-345Insufficient Verification of Data Authenticity (opens in a new tab)
Class weaknessOWASP Top 10 A08:2025: Software or Data Integrity Failures (opens in a new tab)
The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
OWASP Cheat Sheets
XML Security (opens in a new tab)
REST Security (opens in a new tab)
JSON Web Token for Java (opens in a new tab)
REST Assessment (opens in a new tab)
Cross-Site Request Forgery Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.2 (opens in a new tab)
V3.5.3 (opens in a new tab)
V13.2.6 (opens in a new tab)
Attack patterns
JSON Hijacking (aka JavaScript Hijacking) (opens in a new tab)
Cache Poisoning (opens in a new tab)
DNS Cache Poisoning (opens in a new tab)
Spoofing of UDDI/ebXML Messages (opens in a new tab)
Application API Message Manipulation via Man-in-the-Middle (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 8 Jul 2026, 13:45 UTC

WeaknessesCWE-287, CWE-345

Technical details

References

Community reviews

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