CVE-2026-42560 is a critical-severity (CVSS 9.1) vulnerability in github.com/go-pkgz/auth. O3 Security confirms whether CVE-2026-42560 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
auth: Patreon provider assigns the same local user ID to every authenticated Patreon account, enabling cross‑user impersonation
Real-World Exposure
github.com/go-pkgz/auth🐹github.com/go-pkgz/auth/v2Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/go-pkgz/auth | ≥ 1.18.0&&< 1.25.2 | 1.25.2 |
| 🐹Go | github.com/go-pkgz/auth/v2 | ≥ 2.0.0&&< 2.1.2 | 2.1.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/go-pkgz/auth. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/go-pkgz/auth to 1.25.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42560 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-42560 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-42560. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-42560 in your dependencies?
O3 detects CVE-2026-42560 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.