CVE-2026-49756 (GCVE-0-2026-49756)
Vulnerability from cvelistv5 – Published: 2026-06-08 15:20 – Updated: 2026-06-08 16:34
VLAI
EPSS
VEX
Title
Multipart form-data header injection in Req via unescaped name/filename/content_type
Summary
Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in wojtekmach Req allows multipart parameter smuggling via attacker-influenced part metadata.
Req.Utils.encode_form_part/2 in lib/req/utils.ex builds the per-part headers by interpolating the caller-supplied name, filename, and content_type values directly into the content-disposition and content-type lines with no escaping or CRLF stripping. A value containing ", \r, or \n closes the surrounding quoted value and starts a new header line; an additional \r\n--<boundary> terminates the current part and prepends a smuggled part of the attacker's choosing.
This is reachable through every supported way of supplying a part. It is particularly easy when value is a %File.Stream{}, because filename then defaults to Path.basename(stream.path) and POSIX filenames may legitimately contain \r and \n. Any application that forwards user-controlled filenames (or field names / MIME types) through Req.post/2 with form_multipart: lets an attacker inject arbitrary headers into the outgoing multipart body or smuggle additional fields and parts into the request the victim service sends downstream.
This issue affects req: from 0.5.3 before 0.6.0.
Severity
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-06-08 16:05 UTC
CWE
- CWE-93 - Improper Neutralization of CRLF Sequences ('CRLF Injection')
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/wojtekmach/req/security/adviso… | vendor-advisoryrelated |
| https://cna.erlef.org/cves/CVE-2026-49756.html | related |
| https://osv.dev/vulnerability/EEF-CVE-2026-49756 | related |
| https://github.com/wojtekmach/req/commit/74506ff2… | patch |
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| wojtekmach | req |
Affected:
0.5.3 , < 0.6.0
(semver)
cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:* |
||
| wojtekmach | req |
Affected:
60253dbe9436cb8e9c738f895032f2e87939b597 , < 74506ff2c5addf74df85d79dc726e9b2e264a8ba
(git)
cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:* |
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-49756",
"options": [
{
"Exploitation": "poc"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-06-08T16:05:54.070488Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-06-08T16:05:58.580Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"references": [
{
"tags": [
"exploit"
],
"url": "https://github.com/wojtekmach/req/security/advisories/GHSA-px9f-whj3-246m"
}
],
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"collectionURL": "https://repo.hex.pm",
"cpes": [
"cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.Req.Utils\u0027"
],
"packageName": "req",
"packageURL": "pkg:hex/req",
"product": "req",
"programFiles": [
"lib/req/utils.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.Req.Utils\u0027:encode_form_part/2"
}
],
"repo": "https://github.com/wojtekmach/req",
"vendor": "wojtekmach",
"versions": [
{
"lessThan": "0.6.0",
"status": "affected",
"version": "0.5.3",
"versionType": "semver"
}
]
},
{
"collectionURL": "https://github.com",
"cpes": [
"cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.Req.Utils\u0027"
],
"packageName": "wojtekmach/req",
"packageURL": "pkg:github/wojtekmach/req",
"product": "req",
"programFiles": [
"lib/req/utils.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.Req.Utils\u0027:encode_form_part/2"
}
],
"repo": "https://github.com/wojtekmach/req.git",
"vendor": "wojtekmach",
"versions": [
{
"lessThan": "74506ff2c5addf74df85d79dc726e9b2e264a8ba",
"status": "affected",
"version": "60253dbe9436cb8e9c738f895032f2e87939b597",
"versionType": "git"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:*",
"versionEndExcluding": "0.6.0",
"versionStartIncluding": "0.5.3",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
],
"operator": "AND"
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Peter Ullrich"
},
{
"lang": "en",
"type": "remediation developer",
"value": "Wojtek Mach"
},
{
"lang": "en",
"type": "analyst",
"value": "Jonatan M\u00e4nnchen / EEF"
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "Improper Neutralization of CRLF Sequences (\u0027CRLF Injection\u0027) vulnerability in wojtekmach Req allows multipart parameter smuggling via attacker-influenced part metadata.\u003cp\u003e\u003ctt\u003e\u0027Elixir.Req.Utils\u0027:encode_form_part/2\u003c/tt\u003e in \u003ctt\u003elib/req/utils.ex\u003c/tt\u003e builds the per-part headers by interpolating the caller-supplied \u003ctt\u003ename\u003c/tt\u003e, \u003ctt\u003efilename\u003c/tt\u003e, and \u003ctt\u003econtent_type\u003c/tt\u003e values directly into the \u003ctt\u003econtent-disposition\u003c/tt\u003e and \u003ctt\u003econtent-type\u003c/tt\u003e lines with no escaping or CRLF stripping. A value containing \u003ctt\u003e\"\u003c/tt\u003e, \u003ctt\u003e\\r\u003c/tt\u003e, or \u003ctt\u003e\\n\u003c/tt\u003e closes the surrounding quoted value and starts a new header line; an additional \u003ctt\u003e\\r\\n--\u0026lt;boundary\u0026gt;\u003c/tt\u003e terminates the current part and prepends a smuggled part of the attacker\u0027s choosing.\u003c/p\u003e\u003cp\u003eThis is reachable through every supported way of supplying a part. It is particularly easy when \u003ctt\u003evalue\u003c/tt\u003e is a \u003ctt\u003e%File.Stream{}\u003c/tt\u003e, because \u003ctt\u003efilename\u003c/tt\u003e then defaults to \u003ctt\u003ePath.basename(stream.path)\u003c/tt\u003e and POSIX filenames may legitimately contain \u003ctt\u003e\\r\u003c/tt\u003e and \u003ctt\u003e\\n\u003c/tt\u003e. Any application that forwards user-controlled filenames (or field names / MIME types) through \u003ctt\u003e\u0027Elixir.Req\u0027:post/2\u003c/tt\u003e with \u003ctt\u003eform_multipart:\u003c/tt\u003e lets an attacker inject arbitrary headers into the outgoing multipart body or smuggle additional fields and parts into the request the victim service sends downstream.\u003c/p\u003e\u003cp\u003eThis issue affects req: from 0.5.3 before 0.6.0.\u003c/p\u003e"
}
],
"value": "Improper Neutralization of CRLF Sequences (\u0027CRLF Injection\u0027) vulnerability in wojtekmach Req allows multipart parameter smuggling via attacker-influenced part metadata.\n\nReq.Utils.encode_form_part/2 in lib/req/utils.ex builds the per-part headers by interpolating the caller-supplied name, filename, and content_type values directly into the content-disposition and content-type lines with no escaping or CRLF stripping. A value containing \", \\r, or \\n closes the surrounding quoted value and starts a new header line; an additional \\r\\n--\u003cboundary\u003e terminates the current part and prepends a smuggled part of the attacker\u0027s choosing.\n\nThis is reachable through every supported way of supplying a part. It is particularly easy when value is a %File.Stream{}, because filename then defaults to Path.basename(stream.path) and POSIX filenames may legitimately contain \\r and \\n. Any application that forwards user-controlled filenames (or field names / MIME types) through Req.post/2 with form_multipart: lets an attacker inject arbitrary headers into the outgoing multipart body or smuggle additional fields and parts into the request the victim service sends downstream.\n\nThis issue affects req: from 0.5.3 before 0.6.0."
}
],
"impacts": [
{
"capecId": "CAPEC-33",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-33 HTTP Request Smuggling"
}
]
},
{
"capecId": "CAPEC-105",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-105 HTTP Request Splitting"
}
]
}
],
"metrics": [
{
"cvssV4_0": {
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "LOCAL",
"baseScore": 2.1,
"baseSeverity": "LOW",
"privilegesRequired": "NONE",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "LOW",
"subIntegrityImpact": "LOW",
"userInteraction": "NONE",
"vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "LOW"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-93",
"description": "CWE-93 Improper Neutralization of CRLF Sequences (\u0027CRLF Injection\u0027)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-06-08T16:34:58.505Z",
"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"shortName": "EEF"
},
"references": [
{
"tags": [
"vendor-advisory",
"related"
],
"url": "https://github.com/wojtekmach/req/security/advisories/GHSA-px9f-whj3-246m"
},
{
"tags": [
"related"
],
"url": "https://cna.erlef.org/cves/CVE-2026-49756.html"
},
{
"tags": [
"related"
],
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-49756"
},
{
"tags": [
"patch"
],
"url": "https://github.com/wojtekmach/req/commit/74506ff2c5addf74df85d79dc726e9b2e264a8ba"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "Multipart form-data header injection in Req via unescaped name/filename/content_type",
"workarounds": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eSanitize attacker-influenced \u003ctt\u003ename\u003c/tt\u003e, \u003ctt\u003efilename\u003c/tt\u003e, and \u003ctt\u003econtent_type\u003c/tt\u003e values before passing them to \u003ctt\u003e\u0027Elixir.Req\u0027:post/2\u003c/tt\u003e with \u003ctt\u003eform_multipart:\u003c/tt\u003e. At minimum, reject (or strip) any value containing \u003ctt\u003e\\r\u003c/tt\u003e, \u003ctt\u003e\\n\u003c/tt\u003e, or \u003ctt\u003e\"\u003c/tt\u003e. When forwarding uploads, derive \u003ctt\u003efilename\u003c/tt\u003e from a normalised string rather than \u003ctt\u003ePath.basename/1\u003c/tt\u003e on a user-controlled path.\u003c/p\u003e"
}
],
"value": "Sanitize attacker-influenced name, filename, and content_type values before passing them to Req.post/2 with form_multipart:. At minimum, reject (or strip) any value containing \\r, \\n, or \". When forwarding uploads, derive filename from a normalised string rather than Path.basename/1 on a user-controlled path."
}
],
"x_generator": {
"engine": "cvelib 1.8.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"assignerShortName": "EEF",
"cveId": "CVE-2026-49756",
"datePublished": "2026-06-08T15:20:24.035Z",
"dateReserved": "2026-06-01T13:45:22.448Z",
"dateUpdated": "2026-06-08T16:34:58.505Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-49756",
"date": "2026-09-27",
"epss": "0.00337",
"percentile": "0.24563"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"collectionURL": "https://repo.hex.pm",
"cpes": [
"cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.Req.Utils\u0027"
],
"packageName": "req",
"packageURL": "pkg:hex/req",
"product": "req",
"programFiles": [
"lib/req/utils.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.Req.Utils\u0027:encode_form_part/2"
}
],
"repo": "https://github.com/wojtekmach/req",
"vendor": "wojtekmach",
"versions": [
{
"lessThan": "0.6.0",
"status": "affected",
"version": "0.5.3",
"versionType": "semver"
}
]
},
{
"collectionURL": "https://github.com",
"cpes": [
"cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.Req.Utils\u0027"
],
"packageName": "wojtekmach/req",
"packageURL": "pkg:github/wojtekmach/req",
"product": "req",
"programFiles": [
"lib/req/utils.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.Req.Utils\u0027:encode_form_part/2"
}
],
"repo": "https://github.com/wojtekmach/req.git",
"vendor": "wojtekmach",
"versions": [
{
"lessThan": "74506ff2c5addf74df85d79dc726e9b2e264a8ba",
"status": "affected",
"version": "60253dbe9436cb8e9c738f895032f2e87939b597",
"versionType": "git"
}
]
}
],
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:*",
"matchCriteriaId": "E3441D9F-1ACB-44AD-905C-F62F2A15C275",
"versionEndExcluding": "0.6.0",
"versionStartIncluding": "0.5.3",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Improper Neutralization of CRLF Sequences (\u0027CRLF Injection\u0027) vulnerability in wojtekmach Req allows multipart parameter smuggling via attacker-influenced part metadata.\n\nReq.Utils.encode_form_part/2 in lib/req/utils.ex builds the per-part headers by interpolating the caller-supplied name, filename, and content_type values directly into the content-disposition and content-type lines with no escaping or CRLF stripping. A value containing \", \\r, or \\n closes the surrounding quoted value and starts a new header line; an additional \\r\\n--\u003cboundary\u003e terminates the current part and prepends a smuggled part of the attacker\u0027s choosing.\n\nThis is reachable through every supported way of supplying a part. It is particularly easy when value is a %File.Stream{}, because filename then defaults to Path.basename(stream.path) and POSIX filenames may legitimately contain \\r and \\n. Any application that forwards user-controlled filenames (or field names / MIME types) through Req.post/2 with form_multipart: lets an attacker inject arbitrary headers into the outgoing multipart body or smuggle additional fields and parts into the request the victim service sends downstream.\n\nThis issue affects req: from 0.5.3 before 0.6.0."
},
{
"lang": "es",
"value": "La vulnerabilidad de Neutralizaci\u00f3n Incorrecta de Secuencias CRLF (\u0027Inyecci\u00f3n CRLF\u0027) en wojtekmach Req permite el contrabando de par\u00e1metros multipart a trav\u00e9s de metadatos de parte influenciados por el atacante.\n\nReq.Utils.encode_form_part/2 en lib/req/utils.ex construye los encabezados por parte interpolando los valores de nombre, nombre de archivo y tipo de contenido suministrados por el llamador directamente en las l\u00edneas de content-disposition y content-type sin escape ni eliminaci\u00f3n de CRLF. Un valor que contiene \", \\r, o \\n cierra el valor entre comillas circundante y comienza una nueva l\u00ednea de encabezado; un \\r\\n--\u003cboundary\u003e adicional termina la parte actual y antepone una parte contrabandeada a elecci\u00f3n del atacante.\n\nEsto es alcanzable a trav\u00e9s de cada forma compatible de suministrar una parte. Es particularmente f\u00e1cil cuando el valor es un %File.Stream{}, porque el nombre de archivo por defecto es Path.basename(stream.path) y los nombres de archivo POSIX pueden contener leg\u00edtimamente \\r y \\n. Cualquier aplicaci\u00f3n que reenv\u00ede nombres de archivo controlados por el usuario (o nombres de campo / tipos MIME) a trav\u00e9s de Req.post/2 con form_multipart: permite a un atacante inyectar encabezados arbitrarios en el cuerpo multipart saliente o contrabandear campos y partes adicionales en la solicitud que el servicio v\u00edctima env\u00eda aguas abajo.\n\nEste problema afecta a req: desde 0.5.3 antes de 0.6.0."
}
],
"id": "CVE-2026-49756",
"lastModified": "2026-08-18T19:15:38.860",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "HIGH",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 3.7,
"baseSeverity": "LOW",
"confidentialityImpact": "NONE",
"integrityImpact": "LOW",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
"version": "3.1"
},
"exploitabilityScore": 2.2,
"impactScore": 1.4,
"source": "nvd@nist.gov",
"type": "Primary"
}
],
"cvssMetricV40": [
{
"cvssData": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "LOCAL",
"availabilityRequirement": "NOT_DEFINED",
"baseScore": 2.1,
"baseSeverity": "LOW",
"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:L/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-2026-49756",
"options": [
{
"exploitation": "poc"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-06-08T16:05:54.070488Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-06-08T16:16:44.040",
"references": [
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"tags": [
"Third Party Advisory",
"Mitigation"
],
"url": "https://cna.erlef.org/cves/CVE-2026-49756.html"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"tags": [
"Patch"
],
"url": "https://github.com/wojtekmach/req/commit/74506ff2c5addf74df85d79dc726e9b2e264a8ba"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"tags": [
"Vendor Advisory"
],
"url": "https://github.com/wojtekmach/req/security/advisories/GHSA-px9f-whj3-246m"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"tags": [
"Third Party Advisory"
],
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-49756"
},
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"tags": [
"Vendor Advisory"
],
"url": "https://github.com/wojtekmach/req/security/advisories/GHSA-px9f-whj3-246m"
}
],
"sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-93"
}
],
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"type": "Secondary"
}
]
}
},
"redhat_vex": {
"current_release_date": "2026-06-09T20:59:41+00:00",
"cve": "CVE-2026-49756",
"id": "CVE-2026-49756",
"initial_release_date": "2026-01-01T00:00:00+00:00",
"product_status:known_not_affected": "1",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "Multipart form-data header injection in Req via unescaped name/filename/content_type",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-49756.json",
"version": "3"
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-49756",
"options": [
{
"Exploitation": "poc"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-06-08T16:05:54.070488Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-06-08T16:05:28.978Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"references": [
{
"tags": [
"exploit"
],
"url": "https://github.com/wojtekmach/req/security/advisories/GHSA-px9f-whj3-246m"
}
],
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"collectionURL": "https://repo.hex.pm",
"cpes": [
"cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.Req.Utils\u0027"
],
"packageName": "req",
"packageURL": "pkg:hex/req",
"product": "req",
"programFiles": [
"lib/req/utils.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.Req.Utils\u0027:encode_form_part/2"
}
],
"repo": "https://github.com/wojtekmach/req",
"vendor": "wojtekmach",
"versions": [
{
"lessThan": "0.6.0",
"status": "affected",
"version": "0.5.3",
"versionType": "semver"
}
]
},
{
"collectionURL": "https://github.com",
"cpes": [
"cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.Req.Utils\u0027"
],
"packageName": "wojtekmach/req",
"packageURL": "pkg:github/wojtekmach/req",
"product": "req",
"programFiles": [
"lib/req/utils.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.Req.Utils\u0027:encode_form_part/2"
}
],
"repo": "https://github.com/wojtekmach/req.git",
"vendor": "wojtekmach",
"versions": [
{
"lessThan": "74506ff2c5addf74df85d79dc726e9b2e264a8ba",
"status": "affected",
"version": "60253dbe9436cb8e9c738f895032f2e87939b597",
"versionType": "git"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:*",
"versionEndExcluding": "0.6.0",
"versionStartIncluding": "0.5.3",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
],
"operator": "AND"
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Peter Ullrich"
},
{
"lang": "en",
"type": "remediation developer",
"value": "Wojtek Mach"
},
{
"lang": "en",
"type": "analyst",
"value": "Jonatan M\u00e4nnchen / EEF"
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "Improper Neutralization of CRLF Sequences (\u0027CRLF Injection\u0027) vulnerability in wojtekmach Req allows multipart parameter smuggling via attacker-influenced part metadata.\u003cp\u003e\u003ctt\u003e\u0027Elixir.Req.Utils\u0027:encode_form_part/2\u003c/tt\u003e in \u003ctt\u003elib/req/utils.ex\u003c/tt\u003e builds the per-part headers by interpolating the caller-supplied \u003ctt\u003ename\u003c/tt\u003e, \u003ctt\u003efilename\u003c/tt\u003e, and \u003ctt\u003econtent_type\u003c/tt\u003e values directly into the \u003ctt\u003econtent-disposition\u003c/tt\u003e and \u003ctt\u003econtent-type\u003c/tt\u003e lines with no escaping or CRLF stripping. A value containing \u003ctt\u003e\"\u003c/tt\u003e, \u003ctt\u003e\\r\u003c/tt\u003e, or \u003ctt\u003e\\n\u003c/tt\u003e closes the surrounding quoted value and starts a new header line; an additional \u003ctt\u003e\\r\\n--\u0026lt;boundary\u0026gt;\u003c/tt\u003e terminates the current part and prepends a smuggled part of the attacker\u0027s choosing.\u003c/p\u003e\u003cp\u003eThis is reachable through every supported way of supplying a part. It is particularly easy when \u003ctt\u003evalue\u003c/tt\u003e is a \u003ctt\u003e%File.Stream{}\u003c/tt\u003e, because \u003ctt\u003efilename\u003c/tt\u003e then defaults to \u003ctt\u003ePath.basename(stream.path)\u003c/tt\u003e and POSIX filenames may legitimately contain \u003ctt\u003e\\r\u003c/tt\u003e and \u003ctt\u003e\\n\u003c/tt\u003e. Any application that forwards user-controlled filenames (or field names / MIME types) through \u003ctt\u003e\u0027Elixir.Req\u0027:post/2\u003c/tt\u003e with \u003ctt\u003eform_multipart:\u003c/tt\u003e lets an attacker inject arbitrary headers into the outgoing multipart body or smuggle additional fields and parts into the request the victim service sends downstream.\u003c/p\u003e\u003cp\u003eThis issue affects req: from 0.5.3 before 0.6.0.\u003c/p\u003e"
}
],
"value": "Improper Neutralization of CRLF Sequences (\u0027CRLF Injection\u0027) vulnerability in wojtekmach Req allows multipart parameter smuggling via attacker-influenced part metadata.\n\nReq.Utils.encode_form_part/2 in lib/req/utils.ex builds the per-part headers by interpolating the caller-supplied name, filename, and content_type values directly into the content-disposition and content-type lines with no escaping or CRLF stripping. A value containing \", \\r, or \\n closes the surrounding quoted value and starts a new header line; an additional \\r\\n--\u003cboundary\u003e terminates the current part and prepends a smuggled part of the attacker\u0027s choosing.\n\nThis is reachable through every supported way of supplying a part. It is particularly easy when value is a %File.Stream{}, because filename then defaults to Path.basename(stream.path) and POSIX filenames may legitimately contain \\r and \\n. Any application that forwards user-controlled filenames (or field names / MIME types) through Req.post/2 with form_multipart: lets an attacker inject arbitrary headers into the outgoing multipart body or smuggle additional fields and parts into the request the victim service sends downstream.\n\nThis issue affects req: from 0.5.3 before 0.6.0."
}
],
"impacts": [
{
"capecId": "CAPEC-33",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-33 HTTP Request Smuggling"
}
]
},
{
"capecId": "CAPEC-105",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-105 HTTP Request Splitting"
}
]
}
],
"metrics": [
{
"cvssV4_0": {
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "LOCAL",
"baseScore": 2.1,
"baseSeverity": "LOW",
"privilegesRequired": "NONE",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "LOW",
"subIntegrityImpact": "LOW",
"userInteraction": "NONE",
"vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "LOW"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-93",
"description": "CWE-93 Improper Neutralization of CRLF Sequences (\u0027CRLF Injection\u0027)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-06-08T16:34:58.505Z",
"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"shortName": "EEF"
},
"references": [
{
"tags": [
"vendor-advisory",
"related"
],
"url": "https://github.com/wojtekmach/req/security/advisories/GHSA-px9f-whj3-246m"
},
{
"tags": [
"related"
],
"url": "https://cna.erlef.org/cves/CVE-2026-49756.html"
},
{
"tags": [
"related"
],
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-49756"
},
{
"tags": [
"patch"
],
"url": "https://github.com/wojtekmach/req/commit/74506ff2c5addf74df85d79dc726e9b2e264a8ba"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "Multipart form-data header injection in Req via unescaped name/filename/content_type",
"workarounds": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eSanitize attacker-influenced \u003ctt\u003ename\u003c/tt\u003e, \u003ctt\u003efilename\u003c/tt\u003e, and \u003ctt\u003econtent_type\u003c/tt\u003e values before passing them to \u003ctt\u003e\u0027Elixir.Req\u0027:post/2\u003c/tt\u003e with \u003ctt\u003eform_multipart:\u003c/tt\u003e. At minimum, reject (or strip) any value containing \u003ctt\u003e\\r\u003c/tt\u003e, \u003ctt\u003e\\n\u003c/tt\u003e, or \u003ctt\u003e\"\u003c/tt\u003e. When forwarding uploads, derive \u003ctt\u003efilename\u003c/tt\u003e from a normalised string rather than \u003ctt\u003ePath.basename/1\u003c/tt\u003e on a user-controlled path.\u003c/p\u003e"
}
],
"value": "Sanitize attacker-influenced name, filename, and content_type values before passing them to Req.post/2 with form_multipart:. At minimum, reject (or strip) any value containing \\r, \\n, or \". When forwarding uploads, derive filename from a normalised string rather than Path.basename/1 on a user-controlled path."
}
],
"x_generator": {
"engine": "cvelib 1.8.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"assignerShortName": "EEF",
"cveId": "CVE-2026-49756",
"datePublished": "2026-06-08T15:20:24.035Z",
"dateReserved": "2026-06-01T13:45:22.448Z",
"dateUpdated": "2026-06-08T16:34:58.505Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
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.
Loading…
Loading…
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Loading…
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
Loading…