CVE-2026-53516: Better Auth improper authentication in OAuth account linking

CVE-2026-53516 · Severity: high · CVSS 8.3 · Published 2026-07-15

Better Auth is a security library used by developers to handle user logins and permissions in TypeScript applications. A flaw in how it links social media accounts (like Google or GitHub) to local user accounts allows an attacker to take over a victim's account. By pre-registering a victim's email address, an attacker can force the victim's legitimate social login to link to the attacker's account, granting the attacker full access to the victim's data and identity within the application.

Technologies: better-auth (npm). Vendors: npm.

Quick answers

Is CVE-2026-53516 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-53516 being exploited in the wild.
How severe is CVE-2026-53516?
High severity, with a CVSS score of 8.3, published 15 July 2026.
Which products and versions are affected?
better-auth (npm) < 1.6.11, SEMVER:introduced=0,fixed=1.6.11.
Is there a fix for CVE-2026-53516?
Yes. better-auth (npm): upgrade to 1.6.11 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-53516 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-53516?
Check whether you run better-auth (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • better-auth (npm): upgrade to 1.6.11 or later
    npm install better-auth@1.6.11

Technical details

An authentication bypass and account takeover vulnerability exists in Better Auth's OAuth implementation. The `handleOAuthUserInfo` function, used by social providers and SSO, implicitly links incoming OAuth identities to existing local user rows based on email matching if the IdP asserts `email_verified: true`. However, it fails to check if the local user row itself is verified. An attacker can exploit this by pre-registering a victim's email via `/sign-up/email` (which creates an unverified row). When the victim later signs in via OAuth, the library links the victim's verified IdP identity to the attacker-controlled local row. This issue is fixed in version 1.6.11 by requiring `dbUser.user.emailVerified === true` for implicit linking.

Affected products

  • better-auth better-auth < 1.6.11

Identifiers

  • CVE-2026-53516
  • GHSA-g38m-r43w-p2q7

Timeline

  • 2026-05-12: patched: Fix merged in PR #9578 and released in v1.6.11
  • 2026-07-15: advisory: CVE-2026-53516 published via GitHub and NVD

References

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