What is CVE-2026-82754?
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.
The record classifies CVE-2026-82754 under weakness class CWE-424. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 28 days ago.
Severity and exploitation probability
- CVSS v4.0 base score
- 6.3 — Medium (derived from score)
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 - EPSS (FIRST)
- 0.3% probability of exploitation in the next 30 days, higher than 31.6% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 4.4/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-09-07, last modified 2026-09-08
Is CVE-2026-82754 being exploited?
It currently carries a trending score of 38 in the Threadlinqs vulnerability feed.
Affected products and versions
- ash-project: ash_authentication_oauth2_server
How to fix CVE-2026-82754
No vendor patch reference has been recorded for CVE-2026-82754 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-82754
No threat campaign in the Threadlinqs corpus currently references CVE-2026-82754, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.
Sources
Enriched from CVE.org, FIRST EPSS. Last verified by Threadlinqs on .