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Critical, CVSS 9.1

auth: Patreon provider assigns the same local user ID to every authenticated Patreon account, enabling cross‑user impersonation

CVE-2026-42560GHSA-f6qq-3m3h-4g42

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/go-pkgz/auth 1.25.2; github.com/go-pkgz/auth/v2 2.1.2), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
9.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS
  • CVE-2026-42560: 0.42% estimated exploitation activity in the next 30 days; percentile 36.01 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary 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. Details The bug is in the Patreon provider's user-mapping logic. Both the root module and the v2 module create a fresh empty token.User{} and then derive the Patreon ID from userInfo.ID before that field has been populated: Affected locations: - provider/providers.go:257 - v2/provider/providers.go:257 At that point, userInfo.ID is still the empty string, so the effective result is always: which is: for every Patreon user. The code appears to have intended…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-f6qq-3m3h-4g42

Agent brief

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# Patch Next advisory brief: CVE-2026-42560

Advisory: auth: Patreon provider assigns the same local user ID to every authenticated Patreon account, enabling cross‑user impersonation
IDs: CVE-2026-42560, GHSA-f6qq-3m3h-4g42
Record: https://patchnext.com/advisories/cve-2026-42560 (revision 1, source checked 26 Oct 2026, 15:20 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/go-pkgz/auth 1.25.2; github.com/go-pkgz/auth/v2 2.1.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/go-pkgz/auth: affected >= 1.18.0, <= 1.25.1; fixed in 1.25.2
- Go github.com/go-pkgz/auth/v2: affected >= 2.0.0, <= 2.1.1; fixed in 2.1.2

## Suggested inspection (read-only)
- Go github.com/go-pkgz/auth: check the installed version with your package manager.
- Go github.com/go-pkgz/auth/v2: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/go-pkgz/auth, github.com/go-pkgz/auth/v2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-f6qq-3m3h-4g42 (GitHub-reviewed advisory GHSA-f6qq-3m3h-4g42 lists affected ranges: Go github.com/go-pkgz/auth >=1.18.0 =2.0.0 <=2.1.1)

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