Vulnerability · Published Aug 1, 2026 · Assigned by VulnCheck

CVE-2026-67328@better-auth/sso before 1.6.21 Account Takeover via SSO

High 8.1

In plain English

A high-severity cross-site scripting in sso from better-auth. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities).

Severity (CVSS 3.1)8.1High

Exploit odds (30 days)0.5%top 57.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

@better-auth/sso versions before 1.6.21 contain multiple authentication bypass vulnerabilities in SSO provider handling that allow attackers to sign in as arbitrary users. Attackers can exploit domain verification parsing mismatches, orphaned provider accounts, unbound SAML assertions, or reflected XSS on logout endpoints to gain unauthorized session access and account takeover.

Affected products (as reported)

Vendor	Product	Versions
better-auth	sso	0 – before 1.6.21
better-auth	sso	1.7.0-beta.0 – before 1.7.0-beta.10

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

References

GitHub Security Advisory (GHSA-prpr-5gj3-qqhg) vendor-advisory
VulnCheck Advisory: @better-auth/sso before 1.6.21 Account Takeover via SSO third-party-advisory