CVE-2026-82756

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Source
https://cve.org/CVERecord?id=CVE-2026-82756
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-82756.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-82756
Aliases
Published
2026-09-07T22:30:55Z
Modified
2026-09-10T03:30:53Z
Severity
  • 6.3 (Medium) CVSS_V4 - 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 CVSS Calculator
Summary
ash_authentication_oauth2_server interpolates a tenant-derived value into the WWW-Authenticate challenge without escaping, allowing header parameter injection
Details

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.

Database specific 
{
    "cna_assigner": "EEF",
    "cwe_ids": [
        "CWE-116"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82756.json",
    "unresolved_ranges": [
        {
            "extracted_events": [
                {
                    "introduced": "99de0a1cacb5ef667c4533278b7c81ca98c00231"
                },
                {
                    "fixed": "09f97476715da031b136eaec7b2cda2363ad8149"
                }
            ],
            "source": "AFFECTED_FIELD"
        }
    ]
}
References

Affected packages

Git / github.com/ash-project/ash_authentication_oauth2_server

Affected ranges

Type
GIT
Repo
https://github.com/ash-project/ash_authentication_oauth2_server
Events
Introduced
34ecef8343573572a10fd1587d40032be54df05b
Fixed
15bde4311e31c925a428f34c02b283307619e2a2
Fixed
09f97476715da031b136eaec7b2cda2363ad8149
Database specific
Show details 
{
    "extracted_events": [
        {
            "introduced": "0.1.3"
        },
        {
            "fixed": "0.3.1"
        }
    ],
    "source": [
        "DESCRIPTION",
        "REFERENCES"
    ]
}

Affected versions

v0.*
v0.1.3
v0.2.0
v0.2.1
v0.2.2
v0.3.0

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-82756.json"