---
id: CVE-2026-82758
title: >-
  Improper Authentication vulnerability in ash-project
  ash_authentication_oauth2_server allows an unauthenticated attacker to
  register OAuth clients even when Dynamic Client Registration is gated by an
  initial access token.


  resolve_secret…
summary: >-
  Improper Authentication vulnerability in ash-project
  ash_authentication_oauth2_server allows an unauthenticated attacker to
  register OAuth clients even when Dynamic Client Registration is gated by an
  initial access token.


  resolve_secret…
severity: medium
cvss: 6.3
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N'
cwe:
  - CWE-287
vendor: ash-project
product: ash_authentication_oauth2_server
affected:
  - ash_authentication_oauth2_server >= 0.1.0 < 0.3.1
  - >-
    ash-project/ash_authentication_oauth2_server >=
    855b578037c5ded18e8a6e60f42e56bde4905fae <
    30a87101871775d27d79f9ad6f29eafa4779e118
published: '2026-09-07'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T15:18:50.977'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-82758'
references:
  - url: 'https://cna.erlef.org/cves/CVE-2026-82758.html'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/ash-project/ash_authentication_oauth2_server/commit/30a87101871775d27d79f9ad6f29eafa4779e118
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-fxc6-vp68-87pw
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://osv.dev/vulnerability/EEF-CVE-2026-82758'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-08T14:40:53.437993Z'
cvssSource: cna
epss: 0.00686
epssPercentile: 0.50697
ingestedAt: '2026-09-08T15:33:26.980Z'
---

## Overview

Improper Authentication vulnerability in ash-project ash_authentication_oauth2_server allows an unauthenticated attacker to register OAuth clients even when Dynamic Client Registration is gated by an initial access token.

resolve_secret/3 in AshAuthentication.Oauth2Server (reached through __resolve_secret__!) treated any return other than {:ok, _} or :error from a configured {module, function, args} or 2-arity-function secret provider as a valid secret, wrapping nil, false, or "" as {:ok, value}. When the initial_access_token resolves to such an empty value, POST /oauth/register compares the presented bearer token against it and the comparison passes with no token supplied, so registration is open although it was configured closed. The same fail-open affected other resolved secrets such as signing_secret.

This issue affects ash_authentication_oauth2_server: from 0.1.0 before 0.3.1.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.