Authlib RFC 7592 examples omit registration-access-token client binding

Exploitation

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

CVSS

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

EPSS

• CVE-2026-116672: 0.27% estimated exploitation activity in the next 30 days; percentile 19.87 (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.

Description

Summary RFC 7592 (OAuth 2.0 Dynamic Client Registration Management Protocol) lets a previously registered client read, update, or delete its own registration, authenticated by a `registration_access_token` issued specifically to that client at registration time. The entire security model of this protocol depends on the server verifying that the token presented in the request actually belongs to the client identified in the request, not merely that the token is valid for some client. Authlib's `ClientConfigurationEndpoint` implements the control flow correctly in structure, calling `authenticate_token`, then `authenticate_client`, then `check_permission`, and treats all three as abstract methods that "Developers MUST implement in subclass." The problem is that the documented example implementations for these methods, taken together exactly as written, never perform the one check that matters: binding the authenticated token to the specific client being accessed. A…

Published by the source

30 Oct 2026, 23:09 UTC

Last modified by the source

30 Oct 2026, 23:15 UTC

Source last checked

31 Oct 2026, 06:15 UTC

1. Revision 2 · amended · 31 Oct 2026

   Amended from osv record GHSA-c73q-w75p-j82v

2. Revision 1 · created · 30 Oct 2026

   Published from ghsa record GHSA-c73q-w75p-j82v

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# Patch Next advisory brief: CVE-2026-116672

Advisory: Authlib RFC 7592 examples omit registration-access-token client binding
IDs: CVE-2026-116672, GHSA-c73q-w75p-j82v
Record: https://patchnext.com/advisories/cve-2026-116672 (revision 2, source checked 31 Oct 2026, 06:15 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: authlib 1.9.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI authlib: affected >= 0.15, < 1.9.1; fixed in 1.9.1

## Suggested inspection (read-only)
- `python -m pip show authlib`: prints the installed version. Run with the environment that serves production active.

## 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 authlib.
- 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-c73q-w75p-j82v (GitHub-reviewed advisory GHSA-c73q-w75p-j82v lists affected ranges: PyPI authlib >=0.15 <=1.9.0)
- Verified: https://osv.dev/vulnerability/GHSA-c73q-w75p-j82v (OSV record GHSA-c73q-w75p-j82v lists affected ranges: PyPI authlib >=0.15 <1.9.1 (fixed))

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