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

> Attackers can bypass SSO authentication via parsing mismatches or XSS to sign in as arbitrary users and take over accounts.

- **Severity:** High 8.6 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 1 Aug 2026
- **Updated:** 8 Oct 2026
- **Also known as:** GHSA-8g2f-78cq-p655, GHSA-prpr-5gj3-qqhg

## What is CVE-2026-67328?

CVE-2026-67328 is a high-severity authentication bypass vulnerability in better-auth sso, published on 1 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### 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.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-67328?


## How do I fix CVE-2026-67328?

No fix has been published for CVE-2026-67328 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-67328 being exploited?

There is no known exploitation of CVE-2026-67328 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-67328 and fix it if it is affected.

What it is: CVE-2026-67328 is a high-severity authentication bypass vulnerability in better-auth sso, published on 1 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-67328 in the wild and no public exploit code.

Affected product: better-auth sso. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-67328/ (Markdown: https://insights.sbomify.com/CVE-2026-67328/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-67328
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-67328
- OSV: https://osv.dev/vulnerability/CVE-2026-67328

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-67328/
Summaries are generated and may contain mistakes; the official description above is the record.