OAuth client redirection via unescaped challenge parameter
Published Sep 7, 2026 · Updated Sep 8, 2026
Header parameter injection in Ash Project ash_authentication_oauth2_server 0.1.3 through 0.3.0 allows remote attackers to redirect client discovery. BearerPlug and RequireScopePlug place a tenant-derived resource_metadata URL inside a quoted WWW-Authenticate value without escaping quotation marks. Exploitation requires a multi-tenant application that derives the tenant from request-controlled data; a crafted tenant appends authentication parameters that direct compliant clients to an attacker-controlled authorization server.
Summary
What happened
Header parameter injection in Ash Project ash_authentication_oauth2_server 0.1.3 through 0.3.0 allows remote attackers to redirect client discovery. BearerPlug and RequireScopePlug place a tenant-derived resource_metadata URL inside a quoted WWW-Authenticate value without escaping quotation marks. Exploitation requires a multi-tenant application that derives the tenant from request-controlled data; a crafted tenant appends authentication parameters that direct compliant clients to an attacker-controlled authorization server.
The record
- CVE
- CVE-2026-82756
- Published
- Sep 7, 2026
- Updated
- Sep 8, 2026
- Vendor
- Ash Project
- Product
- ash_authentication_oauth2_server
- Classifications
- CWE-116, CAPEC-153
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 7, 2026CVE publishedPublication date reported by the CVE source.
- Sep 8, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0.1.3 <0.3.1
- Affected versionversion=99de0a1cacb5ef667c4533278b7c81ca98c00231 <09f97476715da031b136eaec7b2cda2363ad8149
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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