# CVE-2026-82754: ash-project ash_authentication_oauth2_server path traversal in OAuth endpoints

Source: https://junglewise.ai/threats/cve-2026-82754-ash-project-ash-authentication-oauth2-server-path-traversal-in  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-07. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-82754 · Severity: info · Published 2026-09-07

ash_authentication_oauth2_server is an Elixir library that provides OAuth2 server functionality for web applications. A configuration flaw exposes OAuth endpoints (register, token, revoke) at an alternate path (/.well-known/) alongside their intended paths (/oauth/), allowing requests to bypass security controls like WAF rules and rate limits that are only applied to the canonical paths.

Technologies: [Ash-Project Ash Authentication Oauth2 Server](https://junglewise.ai/threats/technologies/ash-authentication-oauth2-server). Vendors: [Ash-Project](https://junglewise.ai/threats/vendors/ash-project).

## Quick answers

**Is CVE-2026-82754 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-82754 being exploited in the wild.

**How severe is CVE-2026-82754?** Informational severity, published 7 September 2026.

**Which products and versions are affected?** Ash-Project Ash Authentication Oauth2 Server 0.1.0 to 0.3.0.

**Is there a fix for CVE-2026-82754?** A patch was published on 0.3.1: Fix available in version 0.3.1 and later Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-82754 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-82754?** Check whether you run Ash-Project Ash Authentication Oauth2 Server at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

This vulnerability stems from improper path protection in the Phoenix router configuration. The oauth2_server_protocol_routes function mounts the same ProtocolRouter at both /oauth and /.well-known prefixes. Because Phoenix strips the matched prefix before dispatching, the full OAuth route table (register, token, revoke) responds to both mount points. An attacker can reach state-changing OAuth operations at /.well-known/register, /.well-known/token, and /.well-known/revoke, circumventing edge controls such as WAF rules, authentication exemptions, or rate limits that are scoped only to the /oauth prefix. The vulnerability affects ash_authentication_oauth2_server versions 0.1.0 through 0.3.0; version 0.3.1 and later include a fix.

## Affected products

- ash-project ash_authentication_oauth2_server 0.1.0 to 0.3.0

## Timeline

- 2026-09-07: disclosed
- 0.3.1: patched: Fix available in version 0.3.1 and later

## References

- [https://repo.hex.pm/](https://repo.hex.pm/)
- [https://github.com/](https://github.com/)

## Related threats

- [ash-project ash_authentication_oauth2_server authentication bypass in client registration](https://junglewise.ai/threats/cve-2026-82758-ash-project-ash-authentication-oauth2-server-authentication)
- [ash-project ash_authentication_oauth2_server SSRF in metadata fetch](https://junglewise.ai/threats/cve-2026-82757-ash-project-ash-authentication-oauth2-server-ssrf-in-metadata)
- [ash-project ash_authentication_oauth2_server parameter injection in WWW-Authenticate header](https://junglewise.ai/threats/cve-2026-82756-ash-project-ash-authentication-oauth2-server-parameter-injection)
- [ash-project ash_authentication_oauth2_server cache poisoning in OAuth discovery metadata](https://junglewise.ai/threats/cve-2026-82755-ash-project-ash-authentication-oauth2-server-cache-poisoning-in)
- [ash-project ash_authentication_oauth2_server unbound resource allocation in /authorize](https://junglewise.ai/threats/cve-2026-82753-ash-project-ash-authentication-oauth2-server-unbound-resource)