{"cve":"CVE-2026-82726","nvd":{"published":"2026-08-31T04:17:29.357","modified":"2026-09-01T21:15:00.147","status":"Deferred","description":"Permissive Regular Expression vulnerability in ash-project ash_phoenix lets a remote client select the tenant an Ash application uses, or degrade the request, by sending a crafted Host header.\n\nAshPhoenix.Helpers.get_subdomain/2 stripped the root domain with String.replace(host, ~r/.?#{root_host}/, \"\"). The root host was interpolated raw, so each . became a wildcard and any metacharacter a pattern, and the replace was global and unanchored, so a match was removed from anywhere in the string. With root_host example.com, Host: foo.exampleXcom.attacker.net returned the tenant foo.attacker.net. A metacharacter-bearing or nil root host degraded the pattern or raised on every request. The comparison was also case-sensitive, so TENANT.EXAMPLE.COM and EXAMPLE.COM slipped past the root-host allowlist. conn.host comes from the client Host header. The fix matches the root host case-insensitively and only as an exact trailing suffix.\n\nThis issue affects ash_phoenix: from 2.1.26 before 2.3.25.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N","score":6.3},"cvss_v3":null,"cwes":["CWE-178","CWE-625"],"references":["https://cna.erlef.org/cves/CVE-2026-82726.html","https://github.com/ash-project/ash_phoenix/commit/8306f29e77526840c89f3cd244996ce7c0fa2cda","https://github.com/ash-project/ash_phoenix/security/advisories/GHSA-rpf8-q9jh-qxrr","https://osv.dev/vulnerability/EEF-CVE-2026-82726","https://github.com/ash-project/ash_phoenix/security/advisories/GHSA-rpf8-q9jh-qxrr"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:50:50.842544443+00:00"},"epss":{"cve":"CVE-2026-82726","score":0.00524,"percentile":0.44451,"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."]}