{"cve":"CVE-2026-82755","nvd":{"published":"2026-09-07T23:16:52.580","modified":"2026-09-08T15:18:50.490","status":"Deferred","description":"Use of Cache Containing Sensitive Information vulnerability in ash-project ash_authentication_oauth2_server allows a shared HTTP cache to serve one tenant's OAuth discovery metadata to another tenant's clients.\n\nThe RFC 8414 and RFC 9728 metadata endpoints in AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter return tenant-specific values (issuer, authorization_endpoint, token_endpoint, jwks_uri) when a tenant is set, but sent them with Cache-Control: public, max-age=3600 and no Vary. When the tenant is derived from something other than the URL (a header or the Host) and a shared cache sits in front, the cache key is the URL alone, so a stored response for one tenant is served to another for up to an hour. Affected clients may then send authorization codes and secrets to the wrong tenant's token endpoint and validate tokens against the wrong keys.\n\nThis issue affects ash_authentication_oauth2_server: from 0.1.3 before 0.3.1.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/SI:L/SA:N","score":6.3},"cvss_v3":null,"cwes":["CWE-524"],"references":["https://cna.erlef.org/cves/CVE-2026-82755.html","https://github.com/ash-project/ash_authentication_oauth2_server/commit/768d87f70e4e97ae1d2bf1606b5bf3f4d03f24a1","https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-crqf-7m54-4hgc","https://osv.dev/vulnerability/EEF-CVE-2026-82755"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:52:03.409947763+00:00"},"epss":{"cve":"CVE-2026-82755","score":0.00658,"percentile":0.51515,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}