{"api_version":"1","generated_at":"2026-08-31T05:21:21+00:00","cve":"CVE-2026-82726","urls":{"html":"https://cve.report/CVE-2026-82726","api":"https://cve.report/api/cve/CVE-2026-82726.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-82726","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-82726"},"summary":{"title":"AshPhoenix get_subdomain maps a crafted or differently-cased Host header to an arbitrary tenant","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.","state":"PUBLISHED","assigner":"EEF","published_at":"2026-08-31 04:17:29","updated_at":"2026-08-31 04:17:29"},"problem_types":["CWE-178","CWE-625","CWE-625 CWE-625 Permissive Regular Expression","CWE-178 CWE-178 Improper Handling of Case Sensitivity"],"metrics":[{"version":"4.0","source":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","type":"Secondary","score":"6.3","severity":"MEDIUM","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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","data":{"version":"4.0","vectorString":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","baseScore":6.3,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"LOW","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","confidentialityRequirement":"NOT_DEFINED","integrityRequirement":"NOT_DEFINED","availabilityRequirement":"NOT_DEFINED","modifiedAttackVector":"NOT_DEFINED","modifiedAttackComplexity":"NOT_DEFINED","modifiedAttackRequirements":"NOT_DEFINED","modifiedPrivilegesRequired":"NOT_DEFINED","modifiedUserInteraction":"NOT_DEFINED","modifiedVulnConfidentialityImpact":"NOT_DEFINED","modifiedVulnIntegrityImpact":"NOT_DEFINED","modifiedVulnAvailabilityImpact":"NOT_DEFINED","modifiedSubConfidentialityImpact":"NOT_DEFINED","modifiedSubIntegrityImpact":"NOT_DEFINED","modifiedSubAvailabilityImpact":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED"}},{"version":"4.0","source":"CNA","type":"CVSS","score":"6.3","severity":"MEDIUM","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","data":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":6.3,"baseSeverity":"MEDIUM","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"LOW","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"LOW","vulnerabilityResponseEffort":"NOT_DEFINED"}}],"references":[{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-82726","name":"https://osv.dev/vulnerability/EEF-CVE-2026-82726","refsource":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://cna.erlef.org/cves/CVE-2026-82726.html","name":"https://cna.erlef.org/cves/CVE-2026-82726.html","refsource":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/ash-project/ash_phoenix/security/advisories/GHSA-rpf8-q9jh-qxrr","name":"https://github.com/ash-project/ash_phoenix/security/advisories/GHSA-rpf8-q9jh-qxrr","refsource":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/ash-project/ash_phoenix/commit/8306f29e77526840c89f3cd244996ce7c0fa2cda","name":"https://github.com/ash-project/ash_phoenix/commit/8306f29e77526840c89f3cd244996ce7c0fa2cda","refsource":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-82726","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-82726","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"ash-project","product":"ash_phoenix","version":"affected 2.1.26 2.3.25 semver","platforms":[]},{"source":"CNA","vendor":"ash-project","product":"ash_phoenix","version":"affected 9a5ea4d377bc263de321d79574872a3dfc4fb541 8306f29e77526840c89f3cd244996ce7c0fa2cda git","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[{"source":"CNA","value":"Peter Ullrich","lang":"en"},{"source":"CNA","value":"Peter Ullrich","lang":"en"},{"source":"CNA","value":"Zach Daniel / Ash Project","lang":"en"},{"source":"CNA","value":"Jonatan Männchen / EEF","lang":"en"}],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ash-project:ash_phoenix:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["'Elixir.AshPhoenix.Helpers'"],"packageName":"ash_phoenix","packageURL":"pkg:hex/ash_phoenix","product":"ash_phoenix","programFiles":["lib/ash_phoenix/helpers.ex"],"programRoutines":[{"name":"'Elixir.AshPhoenix.Helpers':get_subdomain/2"}],"repo":"https://github.com/ash-project/ash_phoenix","vendor":"ash-project","versions":[{"lessThan":"2.3.25","status":"affected","version":"2.1.26","versionType":"semver"}]},{"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ash-project:ash_phoenix:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["'Elixir.AshPhoenix.Helpers'"],"packageName":"ash-project/ash_phoenix","packageURL":"pkg:github/ash-project/ash_phoenix","product":"ash_phoenix","programFiles":["lib/ash_phoenix/helpers.ex"],"programRoutines":[{"name":"'Elixir.AshPhoenix.Helpers':get_subdomain/2"}],"repo":"https://github.com/ash-project/ash_phoenix","vendor":"ash-project","versions":[{"lessThan":"8306f29e77526840c89f3cd244996ce7c0fa2cda","status":"affected","version":"9a5ea4d377bc263de321d79574872a3dfc4fb541","versionType":"git"}]}],"configurations":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>The application uses subdomain-based multitenancy via <code>AshPhoenix.Helpers.get_subdomain/2</code> (for example through <code>AshPhoenix.LiveView.SubdomainHook</code>) to select the tenant from the request host.</p>"},{"base64":false,"type":"text/markdown","value":"The application uses subdomain-based multitenancy via `AshPhoenix.Helpers.get_subdomain/2` (for example through `AshPhoenix.LiveView.SubdomainHook`) to select the tenant from the request host."}],"value":"The application uses subdomain-based multitenancy via AshPhoenix.Helpers.get_subdomain/2 (for example through AshPhoenix.LiveView.SubdomainHook) to select the tenant from the request host."}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:ash-project:ash_phoenix:*:*:*:*:*:*:*:*","versionEndExcluding":"2.3.25","versionStartIncluding":"2.1.26","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"finder","value":"Peter Ullrich"},{"lang":"en","type":"reporter","value":"Peter Ullrich"},{"lang":"en","type":"remediation developer","value":"Zach Daniel / Ash Project"},{"lang":"en","type":"coordinator","value":"Jonatan Männchen / EEF"}],"descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>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 <code>Host</code> header.</p>\n<p><code>AshPhoenix.Helpers.get_subdomain/2</code> stripped the root domain with <code>String.replace(host, ~r/.?#{root_host}/, \"\")</code>. The root host was interpolated raw, so each <code>.</code> 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 <code>root_host</code> <code>example.com</code>, <code>Host: foo.exampleXcom.attacker.net</code> returned the tenant <code>foo.attacker.net</code>. A metacharacter-bearing or <code>nil</code> root host degraded the pattern or raised on every request. The comparison was also case-sensitive, so <code>TENANT.EXAMPLE.COM</code> and <code>EXAMPLE.COM</code> slipped past the root-host allowlist. <code>conn.host</code> comes from the client <code>Host</code> header. The fix matches the root host case-insensitively and only as an exact trailing suffix.</p>\n<p>This issue affects ash_phoenix: from 2.1.26 before 2.3.25.</p>"},{"base64":false,"type":"text/markdown","value":"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\n`AshPhoenix.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."}],"value":"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."}],"impacts":[{"capecId":"CAPEC-153","descriptions":[{"lang":"en","value":"CAPEC-153 Input Data Manipulation"}]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":6.3,"baseSeverity":"MEDIUM","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"LOW","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"LOW","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-625","description":"CWE-625 Permissive Regular Expression","lang":"en","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-178","description":"CWE-178 Improper Handling of Case Sensitivity","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-08-31T03:05:38.612Z","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","shortName":"EEF"},"references":[{"tags":["vendor-advisory","related"],"url":"https://github.com/ash-project/ash_phoenix/security/advisories/GHSA-rpf8-q9jh-qxrr"},{"tags":["related"],"url":"https://cna.erlef.org/cves/CVE-2026-82726.html"},{"tags":["related"],"url":"https://osv.dev/vulnerability/EEF-CVE-2026-82726"},{"tags":["patch"],"url":"https://github.com/ash-project/ash_phoenix/commit/8306f29e77526840c89f3cd244996ce7c0fa2cda"}],"source":{"discovery":"EXTERNAL"},"title":"AshPhoenix get_subdomain maps a crafted or differently-cased Host header to an arbitrary tenant"}},"cveMetadata":{"assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","assignerShortName":"EEF","cveId":"CVE-2026-82726","datePublished":"2026-08-31T03:05:38.612Z","dateReserved":"2026-08-31T00:59:08.960Z","dateUpdated":"2026-08-31T03:05:38.612Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-31 04:17:29","lastModifiedDate":"2026-08-31 04:17:29","problem_types":["CWE-178","CWE-625","CWE-625 CWE-625 Permissive Regular Expression","CWE-178 CWE-178 Improper Handling of Case Sensitivity"],"metrics":{"cvssMetricV40":[{"source":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","type":"Secondary","cvssData":{"version":"4.0","vectorString":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","baseScore":6.3,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"LOW","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","confidentialityRequirement":"NOT_DEFINED","integrityRequirement":"NOT_DEFINED","availabilityRequirement":"NOT_DEFINED","modifiedAttackVector":"NOT_DEFINED","modifiedAttackComplexity":"NOT_DEFINED","modifiedAttackRequirements":"NOT_DEFINED","modifiedPrivilegesRequired":"NOT_DEFINED","modifiedUserInteraction":"NOT_DEFINED","modifiedVulnConfidentialityImpact":"NOT_DEFINED","modifiedVulnIntegrityImpact":"NOT_DEFINED","modifiedVulnAvailabilityImpact":"NOT_DEFINED","modifiedSubConfidentialityImpact":"NOT_DEFINED","modifiedSubIntegrityImpact":"NOT_DEFINED","modifiedSubAvailabilityImpact":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"82726","Ordinal":"1","Title":"AshPhoenix get_subdomain maps a crafted or differently-cased Hos","CVE":"CVE-2026-82726","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"82726","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"AshPhoenix get_subdomain maps a crafted or differently-cased Hos"}]}}}