ash-project ash_authentication_oauth2_server up to 0.3.0 information disclosure

Summaryinfo

A vulnerability categorized as problematic has been discovered in ash-project ash_authentication_oauth2_server up to 0.3.0. The affected element is the function AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter. Such manipulation leads to information disclosure. This vulnerability is referenced as CVE-2026-82755. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability was found in ash-project ash_authentication_oauth2_server up to 0.3.0. It has been rated as problematic. Affected by this issue is the function AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter. The manipulation with an unknown input leads to a information disclosure vulnerability. Using CWE to declare the problem leads to CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Impacted is confidentiality. CVE summarizes:

Use of Cache Containing Sensitive Information vulnerability in ash-project ash_authentication_oauth2_server allows a shared HTTP cache to serve one tenant's OAuth discovery metadata to another tenant's clients. The RFC 8414 and RFC 9728 metadata endpoints in AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter return tenant-specific values (issuer, authorization_endpoint, token_endpoint, jwks_uri) when a tenant is set, but sent them with Cache-Control: public, max-age=3600 and no Vary. When the tenant is derived from something other than the URL (a header or the Host) and a shared cache sits in front, the cache key is the URL alone, so a stored response for one tenant is served to another for up to an hour. Affected clients may then send authorization codes and secrets to the wrong tenant's token endpoint and validate tokens against the wrong keys. This issue affects ash_authentication_oauth2_server: from 0.1.3 before 0.3.1.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-82755 since 08/31/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1592.

Upgrading to version 0.3.1 eliminates this vulnerability.

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Productinfo

Type

• Project Management Software

Vendor

• ash-project

Name

• ash_authentication_oauth2_server

Version

• 0.1
• 0.2
• 0.3.0

Website

• Product: https://github.com/ash-project/ash_authentication_oauth2_server/

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