Description
Improper Protection of Alternate Path vulnerability in ash-project ash_authentication_oauth2_server exposes the state-changing OAuth endpoints under an unintended URL prefix, bypassing controls scoped to the canonical prefix.

oauth2_server_protocol_routes/1 in AshAuthentication.Phoenix.Oauth2Server.Router forwards the same ProtocolRouter at both the /oauth prefix and the /.well-known prefix. Phoenix forward strips the matched prefix before dispatch, so the full route table answers under both mounts, and POST /register, POST /token, and POST /revoke are reachable as /.well-known/register, /.well-known/token, and /.well-known/revoke. Edge controls such as WAF rules, rate limits, or authentication exemptions written against the /oauth paths, or that allow-list /.well-known as unauthenticated, do not apply to the alias.

This issue affects ash_authentication_oauth2_server: from 0.1.0 before 0.3.1.
Published: 2026-09-07
Score: 6.3 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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History

Mon, 07 Sep 2026 22:45:00 +0000

Type Values Removed Values Added
Description Improper Protection of Alternate Path vulnerability in ash-project ash_authentication_oauth2_server exposes the state-changing OAuth endpoints under an unintended URL prefix, bypassing controls scoped to the canonical prefix. oauth2_server_protocol_routes/1 in AshAuthentication.Phoenix.Oauth2Server.Router forwards the same ProtocolRouter at both the /oauth prefix and the /.well-known prefix. Phoenix forward strips the matched prefix before dispatch, so the full route table answers under both mounts, and POST /register, POST /token, and POST /revoke are reachable as /.well-known/register, /.well-known/token, and /.well-known/revoke. Edge controls such as WAF rules, rate limits, or authentication exemptions written against the /oauth paths, or that allow-list /.well-known as unauthenticated, do not apply to the alias. This issue affects ash_authentication_oauth2_server: from 0.1.0 before 0.3.1.
Title ash_authentication_oauth2_server aliases every protocol endpoint under /.well-known, bypassing path-scoped controls
First Time appeared Ash-project
Ash-project ash Authentication Oauth2 Server
Weaknesses CWE-424
CPEs cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*
Vendors & Products Ash-project
Ash-project ash Authentication Oauth2 Server
References
Metrics cvssV4_0

{'score': 6.3, 'vector': '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'}


Subscriptions

Ash-project Ash Authentication Oauth2 Server
cve-icon MITRE

Status: PUBLISHED

Assigner: EEF

Published:

Updated: 2026-09-07T22:23:56.762Z

Reserved: 2026-08-31T01:00:10.817Z

Link: CVE-2026-82754

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-07T23:16:52.403

Modified: 2026-09-07T23:16:52.403

Link: CVE-2026-82754

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses
  • CWE-424

    Improper Protection of Alternate Path