# CVE-2026-110863: Better Auth @better-auth/sso before 1.7.3 Authentication Bypass via Personal SSO Providers

> Authenticated users can hijack other accounts by registering a personal SSO provider with a copied issuer or entity ID, bypassing account lookup checks.

- **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:** 14 Oct 2026
- **Updated:** 16 Oct 2026
- **Also known as:** GHSA-47gc-4jpf-3mgv, GHSA-mx9r-x6ww-qjw9

## What is CVE-2026-110863?

CVE-2026-110863 is a high-severity authentication bypass vulnerability in better-auth sso, published on 14 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Better Auth @better-auth/sso from 1.7.0-rc.2 before 1.7.3 contains an authentication bypass vulnerability that allows authenticated users to sign in as other users by registering a personal SSO provider. Attackers can copy a legitimate provider's OIDC issuer or SAML entity ID and assert a victim's subject or NameID, because account lookup ignores providerId, creating sessions for victim accounts.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-110863?


## How do I fix CVE-2026-110863?

No fix has been published for CVE-2026-110863 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-110863 being exploited?

There is no known exploitation of CVE-2026-110863 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-110863 and fix it if it is affected.

What it is: CVE-2026-110863 is a high-severity authentication bypass vulnerability in better-auth sso, published on 14 Oct 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-2026-110863 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-2026-110863/ (Markdown: https://insights.sbomify.com/CVE-2026-110863/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-110863
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-110863
- OSV: https://osv.dev/vulnerability/CVE-2026-110863

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-110863/
Summaries are generated and may contain mistakes; the official description above is the record.