{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-49756", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "state": "PUBLISHED", "assignerShortName": "EEF", "dateReserved": "2026-06-01T13:45:22.448Z", "datePublished": "2026-06-08T15:20:24.035Z", "dateUpdated": "2026-06-08T16:34:58.505Z" }, "containers": { "cna": { "affected": [ { "collectionURL": "https://repo.hex.pm", "cpes": [ "cpe:2.3:a:wojtekmach:req:*:*:*:*:*:*:*:*" ], "defaultStatus": "unaffected", "modules": [ "'Elixir.Req.Utils'" ], "packageName": "req", "packageURL": "pkg:hex/req", "product": "req", "programFiles": [ "lib/req/utils.ex" ], "programRoutines": [ { "name": "'Elixir.Req.Utils':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": [ "'Elixir.Req.Utils'" ], "packageName": "wojtekmach/req", "packageURL": "pkg:github/wojtekmach/req", "product": "req", "programFiles": [ "lib/req/utils.ex" ], "programRoutines": [ { "name": "'Elixir.Req.Utils':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 Männchen / EEF" } ], "descriptions": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "value": "Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in wojtekmach Req allows multipart parameter smuggling via attacker-influenced part metadata.

'Elixir.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 'Elixir.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.

" } ], "value": "Improper Neutralization of CRLF Sequences ('CRLF Injection') 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-- terminates the current part and prepends a smuggled part of the attacker's 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 ('CRLF Injection')", "lang": "en", "type": "CWE" } ] } ], "providerMetadata": { "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-06-08T16:34:58.505Z" }, "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": "

Sanitize attacker-influenced name, filename, and content_type values before passing them to 'Elixir.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.

" } ], "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" } }, "adp": [ { "references": [ { "url": "https://github.com/wojtekmach/req/security/advisories/GHSA-px9f-whj3-246m", "tags": [ "exploit" ] } ], "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-06-08T16:05:54.070488Z", "id": "CVE-2026-49756", "options": [ { "Exploitation": "poc" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-06-08T16:05:58.580Z" } } ] } }