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VulnerabilityCVE-2026-82756Published 2026-09-07

CVE-2026-82756 — ash-project ash_authentication_oauth2_server

medium (derived)

As of 2026-09-08, CVE-2026-82756 is a Medium-severity (band derived from the CVSS v4.0 score, not stated by the CNA) vulnerability in ash-project ash_authentication_oauth2_server, CVSS v4.0 6.3, EPSS 0.3% (31.0th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-82756 as of 2026-09-08; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

CVSS v4.0
6.3/10Medium (derived)
EPSS
0.3%Higher than 31.0% of scored CVEs
CISA KEV
NoNot in the KEV catalog
Tracked threats
0None linked yet
Priority
4.4/10Threadlinqs triage score
Published
Updated 2026-09-08
CVSS v4.0 6.3 (Medium, derived from score) · EPSS 0.3% (higher than 31.0% of all scored CVEs) · Priority 4.4/10 · Published 2026-09-07

Last updated:

What is CVE-2026-82756?

Improper Encoding or Escaping of Output vulnerability in ash-project ash_authentication_oauth2_server allows an unauthenticated attacker to inject arbitrary authentication parameters into the WWW-Authenticate challenge header. BearerPlug and RequireScopePlug built the Bearer resource_metadata="..." challenge by interpolating a resource_metadata URL derived from the request tenant directly into the quoted value. In a multi-tenant application that sets the Ash tenant from request-controlled data (a subdomain, the Host, a path segment, or a header), a tenant containing a " closes the quoted value and appends attacker-chosen auth-params, including a second resource_metadata URL pointing at an attacker-controlled authorization server that spec-following clients follow. Carriage returns and line feeds are rejected by Plug, so this is parameter injection within one header, not response splitting. This issue affects ash_authentication_oauth2_server: from 0.1.3 before 0.3.1.

The record classifies CVE-2026-82756 under weakness class CWE-116. 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:L/SI:L/SA:N
EPSS (FIRST)
0.3% probability of exploitation in the next 30 days, higher than 31.0% 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-2026-82756 being exploited?

It currently carries a trending score of 38 in the Threadlinqs vulnerability feed.

Affected products and versions

How to fix CVE-2026-82756

No vendor patch reference has been recorded for CVE-2026-82756 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-2026-82756

No threat campaign in the Threadlinqs corpus currently references CVE-2026-82756, 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, NVD, FIRST EPSS. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.

Vendor advisory and patch

Other references