CVE-2026-42560 auth: Patreon provider assigns the same local user ID to every authenticated Patreon account, enabling cross‑user impersonation
The Patreon OAuth provider assigns identical local IDs to all users, allowing attackers to impersonate others and access their accounts.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42560?
CVE-2026-42560 is a critical authentication bypass vulnerability in go-pkgz auth, published on 9 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
auth provides authentication via oauth2, direct and email. From versions 1.18.0 to before 1.25.2 and 2.0.0 to before 2.1.2, the Patreon OAuth provider maps every authenticated Patreon account to the same local user.ID, instead of deriving a unique ID from the Patreon account returned by Patreon. In practice, this means all Patreon-authenticated users of an application using this library are collapsed into a single local identity. Any application that trusts token.User.ID as the stable account key can end up mixing or fully merging unrelated Patreon users, which can lead to cross-account access, privilege confusion, and subscription-state leakage. This issue has been patched in versions 1.25.2 and 2.1.2.
Weakness: CWE-287
Which versions are affected by CVE-2026-42560?
6 open source packages ship an affected version, including github.com/go-pkgz/auth and github.com/go-pkgz/auth/v2.
| Package | Affected | Fixed in |
|---|---|---|
github.com/go-pkgz/auth Go | From 1.18.0 | 1.25.2 |
github.com/go-pkgz/auth Go | From 1.18.0 | 1.25.2 |
github.com/go-pkgz/auth Go | From 1.18.0 | 1.25.2 |
github.com/go-pkgz/auth/v2 Go | From 2.0.0 | 2.1.2 |
github.com/go-pkgz/auth/v2 Go | From 2.0.0 | 2.1.2 |
github.com/go-pkgz/auth/v2 Go | From 2.0.0 | 2.1.2 |
How do I fix CVE-2026-42560?
Upgrade github.com/go-pkgz/auth to 1.25.2 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-42560 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42560 exists.
Sources
Also known as GHSA-f6qq-3m3h-4g42, GO-2026-5348.