FKIE_CVE-2026-82726
Vulnerability from fkie_nvd - Published: 2026-08-31 04:17 - Updated: 2026-09-01 21:15
Severity
Summary
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.
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.
This issue affects ash_phoenix: from 2.1.26 before 2.3.25.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"collectionURL": "https://repo.hex.pm",
"cpes": [
"cpe:2.3:a:ash-project:ash_phoenix:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.AshPhoenix.Helpers\u0027"
],
"packageName": "ash_phoenix",
"packageURL": "pkg:hex/ash_phoenix",
"product": "ash_phoenix",
"programFiles": [
"lib/ash_phoenix/helpers.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.AshPhoenix.Helpers\u0027: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": [
"\u0027Elixir.AshPhoenix.Helpers\u0027"
],
"packageName": "ash-project/ash_phoenix",
"packageURL": "pkg:github/ash-project/ash_phoenix",
"product": "ash_phoenix",
"programFiles": [
"lib/ash_phoenix/helpers.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.AshPhoenix.Helpers\u0027:get_subdomain/2"
}
],
"repo": "https://github.com/ash-project/ash_phoenix",
"vendor": "ash-project",
"versions": [
{
"lessThan": "8306f29e77526840c89f3cd244996ce7c0fa2cda",
"status": "affected",
"version": "9a5ea4d377bc263de321d79574872a3dfc4fb541",
"versionType": "git"
}
]
}
],
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"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."
}
],
"id": "CVE-2026-82726",
"lastModified": "2026-09-01T21:15:00.147",
"metrics": {
"cvssMetricV40": [
{
"cvssData": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "NETWORK",
"availabilityRequirement": "NOT_DEFINED",
"baseScore": 6.3,
"baseSeverity": "MEDIUM",
"confidentialityRequirement": "NOT_DEFINED",
"exploitMaturity": "NOT_DEFINED",
"integrityRequirement": "NOT_DEFINED",
"modifiedAttackComplexity": "NOT_DEFINED",
"modifiedAttackRequirements": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
"modifiedPrivilegesRequired": "NOT_DEFINED",
"modifiedSubAvailabilityImpact": "NOT_DEFINED",
"modifiedSubConfidentialityImpact": "NOT_DEFINED",
"modifiedSubIntegrityImpact": "NOT_DEFINED",
"modifiedUserInteraction": "NOT_DEFINED",
"modifiedVulnAvailabilityImpact": "NOT_DEFINED",
"modifiedVulnConfidentialityImpact": "NOT_DEFINED",
"modifiedVulnIntegrityImpact": "NOT_DEFINED",
"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/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",
"version": "4.0",
"vulnAvailabilityImpact": "LOW",
"vulnConfidentialityImpact": "LOW",
"vulnIntegrityImpact": "LOW",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-82726",
"options": [
{
"exploitation": "poc"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-08-31T14:47:10.055608Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-08-31T04:17:29.357",
"references": [
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://cna.erlef.org/cves/CVE-2026-82726.html"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://github.com/ash-project/ash_phoenix/commit/8306f29e77526840c89f3cd244996ce7c0fa2cda"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://github.com/ash-project/ash_phoenix/security/advisories/GHSA-rpf8-q9jh-qxrr"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-82726"
},
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"url": "https://github.com/ash-project/ash_phoenix/security/advisories/GHSA-rpf8-q9jh-qxrr"
}
],
"sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"vulnStatus": "Deferred",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-178"
},
{
"lang": "en",
"value": "CWE-625"
}
],
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"type": "Secondary"
}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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