How should we interpret CVSS severity scores?

CVSS estimates technical severity, but it does not automatically equal business risk. Prioritize using context like internet exposure, asset criticality, known exploitation, and whether compensating controls exist. A Medium CVSS on an exposed production system can be more urgent than a Critical on an isolated non-production host.

Vulnerability Database

Q: What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

Q: What's the difference between a vulnerability, an exploit, and a zero-day?

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. Risk increases sharply when exploitation becomes reliable or widespread.

Q: Why do vulnerabilities keep reappearing in our environment?

Recurring findings usually come from incomplete asset discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host.

Q: How do we prioritize remediation without burning out the team?

Use a repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress so remediation is steady, not reactive.

Q: How can SynScan help reduce vulnerability risk over time?

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.

363,159

Total vulnerabilities in the database

Better Auth: Account takeover via pre-account hijacking on magic-link and email-OTP sign-in — better-auth

Improper Authentication

Am I affected

You are affected if all of the following hold:

You run a better-auth version below 1.6.22, or a 1.7.0-beta below 1.7.0-beta.10.
You enable the magic-link plugin or the email-OTP plugin.
You also enable email and password sign-up with open registration.
An account can exist at an address before its owner first signs in with the passwordless flow.

Summary

An attacker can keep password access to a victim's account after the victim starts using it. The attack runs in three steps. First, with open registration, the attacker signs up using the victim's email and a password the attacker picks. The account stays unverified, so the attacker cannot use it yet. Later the real owner signs in with a magic link or an email OTP. That step marks the account verified, and the attacker's password now works on it.

Details

When an account already exists for an address, magic-link verification and email-OTP sign-in both sign in to that account. They mark it verified and issue a session. Before the fix, neither one removed a password set while the account was still unverified. Neither one revoked existing sessions. So a password set before anyone proved control of the mailbox kept working after the owner proved control.

This is a pre-account-hijacking weakness. It is the same class as the OAuth advisory GHSA-g38m-r43w-p2q7, applied to the passwordless email flows. Requiring email verification does not stop it. The verification step is the exact moment that turns the planted account into a usable one.

The fix treats current proof of control over the address as authoritative. When either flow finds an account whose email was never confirmed, it now removes the password and revokes existing sessions first. Only then does it mark the account verified and issue the new session. The owner signs in as before. Only access created before the proof is removed.

Patches

Upgrade to better-auth 1.6.22 or later on the stable line. On the 1.7 pre-release line, upgrade to 1.7.0-beta.10 or later. Earlier 1.7 betas, up to and including 1.7.0-beta.9, still contain the bug.

Workarounds

If you cannot upgrade right away, you can lower the risk in two ways. Require email verification before you accept any password on an account. Remove unverified accounts quickly, so an address cannot sit reserved for long. Both steps shrink the opening, but they do not close it. Upgrading is the real fix.

Impact

The attacker gains lasting password access to an account the victim depends on, alongside the victim. From there the attacker can read and change the victim's data. The attacker can also reset the credentials and lock the victim out. The takeover only completes when the victim signs in through the passwordless flow. It also needs a setup that pairs that flow with open email and password sign-up.

Credit

Reported by the Vercel security team.

Published: Jul 24, 2026
Updated: Jul 25, 2026
GHSA: GHSA-qq9h-g4jm-xgf3
Severity: High
Exploit:
CISA KEV:

CVSS v3:

Severity: High
Score: 8.3
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L

CWEs:

OWASP TOP 10:

A2 - Broken Authentication

Affected Software
References

Software	From	Fixed in
better-auth	1.1.3	1.6.22
better-auth	1.7.0-beta.0	1.7.0-beta.10

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Frequently Asked Questions

What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.