FKIE_CVE-2026-43972
Vulnerability from fkie_nvd - Published: 2026-06-08 15:16 - Updated: 2026-07-23 07:10
Severity
Summary
Origin Validation Error vulnerability in ninenines gun (gun_http2 module) allows cross-origin cookie injection via unvalidated HTTP/2 PUSH_PROMISE authority.
In gun_http2:push_promise_frame/7, the :authority pseudo-header from an incoming PUSH_PROMISE frame is stored verbatim into the promised stream record without checking that it matches the connection's origin. When gun_http2:headers_frame/9 later processes the response headers for the promised stream, it calls gun_cookies:set_cookie_header/7 with the unvalidated server-supplied authority before any status branching and before user code can act. This violates RFC 7540 §10.6 / RFC 9113 §8.4, which require receivers to treat as a protocol error any push for a resource the server is not authoritative for.
A malicious or compromised HTTP/2 server can plant cookies scoped to arbitrary third-party domains into the client's shared cookie store. This enables session fixation attacks against those domains and, if the planted cookie overrides a legitimate session token, may result in account takeover. No user interaction beyond making a normal HTTP/2 request to the attacker-controlled server is required.
This issue affects gun: from 2.0.0 before 2.4.0.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"cpes": [
"cpe:2.3:a:ninenines:gun:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"gun_http2"
],
"packageName": "gun",
"packageURL": "pkg:hex/gun",
"product": "gun",
"programFiles": [
"src/gun_http2.erl"
],
"programRoutines": [
{
"name": "gun_http2:push_promise_frame/7"
},
{
"name": "gun_http2:headers_frame/9"
}
],
"repo": "https://github.com/ninenines/gun",
"vendor": "ninenines",
"versions": [
{
"lessThan": "2.4.0",
"status": "affected",
"version": "2.0.0",
"versionType": "semver"
}
]
},
{
"collectionURL": "https://github.com",
"cpes": [
"cpe:2.3:a:ninenines:gun:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"gun_http2"
],
"packageName": "ninenines/gun",
"packageURL": "pkg:github/ninenines/gun",
"product": "gun",
"programFiles": [
"src/gun_http2.erl"
],
"programRoutines": [
{
"name": "gun_http2:push_promise_frame/7"
},
{
"name": "gun_http2:headers_frame/9"
}
],
"repo": "https://github.com/ninenines/gun.git",
"vendor": "ninenines",
"versions": [
{
"lessThan": "567863ff53802fed21c3b3f25812db7f7ae29676",
"status": "affected",
"version": "871989eef53663285c165fdfb83a5918ebe00d41",
"versionType": "git"
}
]
}
],
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Origin Validation Error vulnerability in ninenines gun (gun_http2 module) allows cross-origin cookie injection via unvalidated HTTP/2 PUSH_PROMISE authority.\n\nIn gun_http2:push_promise_frame/7, the :authority pseudo-header from an incoming PUSH_PROMISE frame is stored verbatim into the promised stream record without checking that it matches the connection\u0027s origin. When gun_http2:headers_frame/9 later processes the response headers for the promised stream, it calls gun_cookies:set_cookie_header/7 with the unvalidated server-supplied authority before any status branching and before user code can act. This violates RFC 7540 \u00a710.6 / RFC 9113 \u00a78.4, which require receivers to treat as a protocol error any push for a resource the server is not authoritative for.\n\nA malicious or compromised HTTP/2 server can plant cookies scoped to arbitrary third-party domains into the client\u0027s shared cookie store. This enables session fixation attacks against those domains and, if the planted cookie overrides a legitimate session token, may result in account takeover. No user interaction beyond making a normal HTTP/2 request to the attacker-controlled server is required.\n\nThis issue affects gun: from 2.0.0 before 2.4.0."
},
{
"lang": "es",
"value": "Vulnerabilidad de error de validaci\u00f3n de origen en ninenines gun (m\u00f3dulo gun_http2) permite la inyecci\u00f3n de cookies de origen cruzado a trav\u00e9s de la autoridad PUSH_PROMISE de HTTP/2 no validada.\n\nEn gun_http2:push_promise_frame/7, el pseudo-encabezado :authority de un frame PUSH_PROMISE entrante se almacena textualmente en el registro del stream prometido sin verificar que coincida con el origen de la conexi\u00f3n. Cuando gun_http2:headers_frame/9 procesa posteriormente los encabezados de respuesta para el stream prometido, llama a gun_cookies:set_cookie_header/7 con la autoridad proporcionada por el servidor no validada antes de cualquier ramificaci\u00f3n de estado y antes de que el c\u00f3digo de usuario pueda actuar. Esto viola RFC 7540 \u00a710.6 / RFC 9113 \u00a78.4, que requieren que los receptores traten como un error de protocolo cualquier push para un recurso para el que el servidor no es autoritativo.\n\nUn servidor HTTP/2 malicioso o comprometido puede insertar cookies con alcance a dominios de terceros arbitrarios en el almac\u00e9n de cookies compartido del cliente. Esto permite ataques de fijaci\u00f3n de sesi\u00f3n contra esos dominios y, si la cookie insertada anula un token de sesi\u00f3n leg\u00edtimo, puede resultar en la toma de control de la cuenta. No se requiere interacci\u00f3n del usuario m\u00e1s all\u00e1 de realizar una solicitud HTTP/2 normal al servidor controlado por el atacante.\n\nEste problema afecta a gun: desde 2.0.0 antes de 2.4.0."
}
],
"id": "CVE-2026-43972",
"lastModified": "2026-07-23T07:10:00.113",
"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": "LOW",
"subIntegrityImpact": "LOW",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "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/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": "NONE",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "LOW",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-43972",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-06-08T15:42:59.352280Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-06-08T15:16:46.290",
"references": [
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://cna.erlef.org/cves/CVE-2026-43972.html"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://github.com/ninenines/gun/commit/567863ff53802fed21c3b3f25812db7f7ae29676"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-43972"
}
],
"sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"vulnStatus": "Awaiting Analysis",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-346"
}
],
"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.
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