---
title: "CVE-2026-42560: auth: Patreon provider assigns the same local user ID to every authenticated Patreon account, enabling cross‑user impersonation"
url: https://erroneo.us/security/cve/CVE-2026-42560/
description: "CVE-2026-42560 (github.com/go-pkgz/auth (Go)): auth provides authentication via oauth2, direct and email. From versions 1.18.0 to before 1.25.2 and 2.0.0 to…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-05-09
date_modified: 2026-05-13
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-42560"
kev: false
cvss: 9.1
epss: 0.00579
license: All rights reserved. Quote with attribution and a link.
---

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

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.6% , percentile 47: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 47% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes github.com/go-pkgz/auth (Go) >= 1.18.0, <= 1.25.1, fixed in 1.25.2 ; github.com/go-pkgz/auth/v2 (Go) >= 2.0.0, <= 2.1.1, fixed in 2.1.2 . Check your lockfile, including transitive dependencies.

## What it is

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

- Go `github.com/go-pkgz/auth` >= 1.18.0, <= 1.25.1 → fixed: 1.25.2
- Go `github.com/go-pkgz/auth/v2` >= 2.0.0, <= 2.1.1 → fixed: 2.1.2

## Affected products (CVE record)

- go-pkgz auth: >= 1.18.0, < 1.25.2, >= 2.0.0, < 2.1.2

## Severity

- GitHub_M CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`
- GitHub CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact partial .
- FIRST EPSS (model of 2026-10-21): 0.58% probability of exploitation activity in the next 30 days; percentile 47.

## Sources

- [GitHub Advisory GHSA-f6qq-3m3h-4g42](https://github.com/advisories/GHSA-f6qq-3m3h-4g42)
- [CVE.org record CVE-2026-42560](https://www.cve.org/CVERecord?id=CVE-2026-42560)
- [NVD entry CVE-2026-42560](https://nvd.nist.gov/vuln/detail/CVE-2026-42560)
- [github.com](https://github.com/go-pkgz/auth/security/advisories/GHSA-f6qq-3m3h-4g42)
- [github.com](https://github.com/go-pkgz/auth/commit/c0b15ee72a8401da83c01781c16636c521f42698)
- [github.com](https://github.com/go-pkgz/auth/releases/tag/v1.25.2)
- [github.com](https://github.com/go-pkgz/auth/releases/tag/v2.1.2)

---
Source page: https://erroneo.us/security/cve/CVE-2026-42560/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt