CVE-2026-43966

{"id": "CVE-2026-43966", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-43966", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-06-08T18:37:59.853576Z"}}], "cvssMetricV40": [{"type": "Secondary", "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 6.3, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/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", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "subIntegrityImpact": "LOW", "vulnIntegrityImpact": "NONE", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "affectedData": [{"cpes": ["cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*"], "repo": "https://github.com/ninenines/cowlib", "vendor": "ninenines", "modules": ["cow_http_struct_hd"], "product": "cowlib", "versions": [{"status": "affected", "version": "2.9.0", "versionType": "semver"}], "packageURL": "pkg:hex/cowlib", "packageName": "cowlib", "programFiles": ["src/cow_http_struct_hd.erl"], "collectionURL": "https://repo.hex.pm", "defaultStatus": "unaffected", "programRoutines": [{"name": "cow_http_struct_hd:escape_string/2"}, {"name": "cow_http_struct_hd:bare_item/1"}]}, {"cpes": ["cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*"], "repo": "https://github.com/ninenines/cowlib", "vendor": "ninenines", "modules": ["cow_http_struct_hd"], "product": "cowlib", "versions": [{"status": "affected", "version": "a8b793db3d6ffe91d62f81baf41b1dab4cd78fb6", "versionType": "git"}], "packageURL": "pkg:github/ninenines/cowlib", "packageName": "ninenines/cowlib", "programFiles": ["src/cow_http_struct_hd.erl"], "collectionURL": "https://github.com", "defaultStatus": "unaffected", "programRoutines": [{"name": "cow_http_struct_hd:escape_string/2"}, {"name": "cow_http_struct_hd:bare_item/1"}]}]}], "published": "2026-06-08T17:16:43.447", "references": [{"url": "https://cna.erlef.org/cves/CVE-2026-43966.html", "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}, {"url": "https://github.com/ninenines/cowboy/commit/f77cb9b5e730e300fffb551db1ba5d1c4ed878ef", "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}, {"url": "https://github.com/ninenines/gun/commit/4f35609eb37109b106a863fc9ba83d7ee64e3e42", "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}, {"url": "https://osv.dev/vulnerability/EEF-CVE-2026-43966", "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}], "vulnStatus": "Awaiting Analysis", "weaknesses": [{"type": "Secondary", "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "description": [{"lang": "en", "value": "CWE-113"}]}], "descriptions": [{"lang": "en", "value": "Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting') vulnerability in ninenines cowlib allows HTTP response splitting via non-VCHAR bytes in structured-fields string values.\n\ncow_http_struct_hd:escape_string/2 in cowlib only escapes \\ and \", passing all other bytes through verbatim. This creates an encoder/decoder asymmetry: the matching parser accepts only printable ASCII (0x20\u20130x7E, excluding \" and \\), but the encoder emits any byte including CR and LF. An application that builds a structured HTTP header via cow_http_struct_hd:item/1 (or a higher-level wrapper such as cow_http_hd:wt_protocol/1) from attacker-controlled input can have \\r\\n injected into the serialized header value. Once on the wire, the injected CRLF terminates the current header and any following bytes are interpreted as a new header, enabling HTTP response splitting.\n\nThis issue affects cowlib from 2.9.0."}, {"lang": "es", "value": "La vulnerabilidad de Neutralizaci\u00f3n Incorrecta de Secuencias CRLF en Encabezados HTTP ('Divisi\u00f3n de Solicitud/Respuesta HTTP') en ninenines cowlib permite la divisi\u00f3n de respuesta HTTP a trav\u00e9s de bytes no VCHAR en valores de cadena de campos estructurados.\n\ncow_http_struct_hd:escape_string/2 en cowlib solo escapa \\ y \", pasando todos los dem\u00e1s bytes textualmente. Esto crea una asimetr\u00eda de codificador/decodificador: el analizador coincidente acepta solo ASCII imprimible (0x20-0x7E, excluyendo \" y \\), pero el codificador emite cualquier byte, incluidos CR y LF. Una aplicaci\u00f3n que construye un encabezado HTTP estructurado a trav\u00e9s de cow_http_struct_hd:item/1 (o un envoltorio de nivel superior como cow_http_hd:wt_protocol/1) desde una entrada controlada por el atacante puede tener \\r\\n inyectado en el valor del encabezado serializado. Una vez en la red, el CRLF inyectado termina el encabezado actual y cualquier byte siguiente se interpreta como un nuevo encabezado, lo que permite la divisi\u00f3n de respuesta HTTP.\n\nEste problema afecta a cowlib desde la versi\u00f3n 2.9.0."}], "lastModified": "2026-07-23T07:10:00.113", "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}