CVE-2026-82753
HighCVSS 8.2Summary
Resource exhaustion vulnerability in ash_authentication_oauth2_server. An unauthenticated attacker can exhaust database storage and memory by sending requests to the /authorize endpoint with many distinct client_id URLs, creating permanent client rows and caching documents without limits.
Risk Assessment
An attacker can cause denial of service by exhausting system resources, leading to service unavailability and potential data loss.
Recommendation
Upgrade ash_authentication_oauth2_server to version 0.3.1 or later, which includes a fix that limits the number of records and the size of fetched documents.
Other vulnerabilities in ash_authentication_oauth2_server
See all- CVE-2026-82758Medium
Vulnerability in ash_authentication_oauth2_server allows an unauthenticated attacker to register OAuth clients even when Dynamic Client Registration is gated by an initial access token. The resolve_secret/3 function treats any return other than {:ok, _} or :error as a valid secret, allowing bypass of protections.
- CVE-2026-82757Medium
SSRF vulnerability in ash_authentication_oauth2_server allows an attacker who controls a client metadata URL and its DNS to make the server connect to internal or loopback addresses. The public_ip?/1 function incorrectly classifies certain address ranges as public, allowing policy bypass.
- CVE-2026-82756Medium
Vulnerability in ash_authentication_oauth2_server allows an unauthenticated attacker to inject arbitrary authentication parameters into the WWW-Authenticate challenge header. The resource_metadata value is interpolated without proper escaping, allowing header modification and redirecting clients to a malicious authorization server.
- CVE-2026-82755Medium
Vulnerability in ash_authentication_oauth2_server allows a shared HTTP cache to serve one tenant's OAuth discovery metadata to another tenant's clients. Responses with metadata are marked as Cache-Control: public without a Vary header, causing responses to be cached and served to other tenants.
- CVE-2026-82754Medium
Vulnerability in ash_authentication_oauth2_server exposes state-changing OAuth endpoints under an unintended URL prefix, bypassing controls scoped to the canonical prefix. Routes are mounted under both /oauth and /.well-known, allowing access to /register, /token, and /revoke via alternative paths.
Original NVD description (English source)
Allocation of Resources Without Limits or Throttling vulnerability in ash-project ash_authentication_oauth2_server allows an unauthenticated attacker to exhaust database storage and memory. The /authorize endpoint is unauthenticated by design. With Client ID Metadata Documents enabled, resolve_client/3 in AshAuthentication.Oauth2Server.CIMD fetches the document for each new URL-shaped client_id and upserts a client row, with no cap on the number of rows, no expiry or garbage collection, and no length bound on the fetched fields; the document was also placed in CIMD.Cache before validation, so even rejected documents held cache memory until their TTL. An attacker serving valid documents at many distinct URLs creates one permanent client row per URL, each able to carry multi-megabyte strings, growing storage and memory without bound. This issue affects ash_authentication_oauth2_server: from 0.3.0 before 0.3.1.