Tinyauth's OIDC authorization codes are not bound to client on token exchange

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:H/A:N

EPSS

• CVE-2026-32245: 0.27% estimated exploitation activity in the next 30 days; percentile 18.52 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The OIDC token endpoint does not verify that the client exchanging an authorization code is the same client the code was issued to. A malicious OIDC client operator can exchange another client's authorization code using their own client credentials, obtaining tokens for users who never authorized their application. This violates RFC 6749 Section 4.1.3. Details When an authorization code is created, StoreCode at internal/service/oidcservice.go:305-322 correctly stores the ClientID alongside the code hash in the database (line 316). During token exchange at internal/controller/oidccontroller.go:267-309, the handler retrieves the code entry at line 268 and validates the redirecturi at line 291, but never compares entry.ClientID against the requesting client's ID (creds.ClientID). The code proceeds directly to GenerateAccessToken at line 299. The developers clearly intended this check to exist, the refresh token flow at internal/service/oidcservice.go:508-510 has the exact guard:…

Published by the source

12 Mar 2026, 16:38 UTC

Last modified by the source

24 Mar 2026, 21:11 UTC

Source last checked

26 Oct 2026, 15:18 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-xg2q-62g2-cvcm

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# Patch Next advisory brief: CVE-2026-32245

Advisory: Tinyauth's OIDC authorization codes are not bound to client on token exchange
IDs: CVE-2026-32245, GHSA-xg2q-62g2-cvcm
Record: https://patchnext.com/advisories/cve-2026-32245 (revision 1, source checked 26 Oct 2026, 15:18 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/steveiliop56/tinyauth 1.0.1-20260311144920-9eb2d33064b7. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/steveiliop56/tinyauth: affected < 1.0.1-20260311144920-9eb2d33064b7; fixed in 1.0.1-20260311144920-9eb2d33064b7

## Suggested inspection (read-only)
- Go github.com/steveiliop56/tinyauth: 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/steveiliop56/tinyauth.
- 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-xg2q-62g2-cvcm (GitHub-reviewed advisory GHSA-xg2q-62g2-cvcm lists affected ranges: Go github.com/steveiliop56/tinyauth >=0 <1.0.1-20260311144920-9eb2d33064b7)

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