Pocket ID: OIDC authorization code validation uses AND instead of OR, allowing cross-client token exchange

Exploitation

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

CVSS

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

EPSS

• CVE-2026-28513: 0.29% estimated exploitation activity in the next 30 days; percentile 21.47 (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 rejects an authorization code only when both the client ID is wrong and the code is expired. This allows cross-client code exchange and expired code reuse. Details backend/internal/service/oidcservice.go:407 && should be ||. Current behavior: | Condition | Expected | Actual | |-----------|----------|--------| | Wrong client + valid code | Reject | Accept | | Correct client + expired code | Reject | Accept | PoC Prerequisite: pocket-id running with APPENV=test and BUILDTAGS=e2etest. The test user (Tim Cook) must have authorized both Nextcloud and Immich OIDC clients (i.e., userauthorizedoidcclients records exist for both). The seed data includes an authorization code auth-code issued for the Nextcloud client. Verified result: HTTP 200 with tokens. The accesstoken audience is 606c7782-... (Immich), despite the authorization code being issued for 3654a746-... (Nextcloud). Impact Any OIDC client operator can exchange authorization codes issued for other…

Published by the source

9 Mar 2026, 17:24 UTC

Last modified by the source

10 Mar 2026, 18:43 UTC

Source last checked

26 Oct 2026, 15:15 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-qh6q-598w-w6m2

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# Patch Next advisory brief: CVE-2026-28513

Advisory: Pocket ID: OIDC authorization code validation uses AND instead of OR, allowing cross-client token exchange
IDs: CVE-2026-28513, GHSA-qh6q-598w-w6m2
Record: https://patchnext.com/advisories/cve-2026-28513 (revision 1, source checked 26 Oct 2026, 15:15 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/pocket-id/pocket-id/backend 0.0.0-20260307173642-b59e35cb59ae. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/pocket-id/pocket-id/backend: affected < 0.0.0-20260307173642-b59e35cb59ae; fixed in 0.0.0-20260307173642-b59e35cb59ae

## Suggested inspection (read-only)
- Go github.com/pocket-id/pocket-id/backend: 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/pocket-id/pocket-id/backend.
- 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-qh6q-598w-w6m2 (GitHub-reviewed advisory GHSA-qh6q-598w-w6m2 lists affected ranges: Go github.com/pocket-id/pocket-id/backend >=0 <0.0.0-20260307173642-b59e35cb59ae)

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