{"api_version":"1","generated_at":"2026-06-08T18:28:40+00:00","cve":"CVE-2026-49756","urls":{"html":"https://cve.report/CVE-2026-49756","api":"https://cve.report/api/cve/CVE-2026-49756.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-49756","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-49756"},"summary":{"title":"Multipart form-data header injection in Req via unescaped name/filename/content_type","description":"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. 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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.","state":"PUBLISHED","assigner":"EEF","published_at":"2026-06-08 16:16:44","updated_at":"2026-06-08 17:16:52"},"problem_types":["CWE-93","CWE-93 CWE-93 Improper Neutralization of CRLF Sequences ('CRLF Injection')"],"metrics":[{"version":"4.0","source":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","type":"Secondary","score":"2.1","severity":"LOW","vector":"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","data":{"version":"4.0","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","baseScore":2.1,"baseSeverity":"LOW","attackVector":"LOCAL","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"LOW","subIntegrityImpact":"LOW","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","confidentialityRequirement":"NOT_DEFINED","integrityRequirement":"NOT_DEFINED","availabilityRequirement":"NOT_DEFINED","modifiedAttackVector":"NOT_DEFINED","modifiedAttackComplexity":"NOT_DEFINED","modifiedAttackRequirements":"NOT_DEFINED","modifiedPrivilegesRequired":"NOT_DEFINED","modifiedUserInteraction":"NOT_DEFINED","modifiedVulnConfidentialityImpact":"NOT_DEFINED","modifiedVulnIntegrityImpact":"NOT_DEFINED","modifiedVulnAvailabilityImpact":"NOT_DEFINED","modifiedSubConfidentialityImpact":"NOT_DEFINED","modifiedSubIntegrityImpact":"NOT_DEFINED","modifiedSubAvailabilityImpact":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED"}},{"version":"4.0","source":"CNA","type":"CVSS","score":"2.1","severity":"LOW","vector":"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","data":{"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"}}],"references":[{"url":"https://cna.erlef.org/cves/CVE-2026-49756.html","name":"https://cna.erlef.org/cves/CVE-2026-49756.html","refsource":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-49756","name":"https://osv.dev/vulnerability/EEF-CVE-2026-49756","refsource":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/wojtekmach/req/security/advisories/GHSA-px9f-whj3-246m","name":"https://github.com/wojtekmach/req/security/advisories/GHSA-px9f-whj3-246m","refsource":"134c704f-9b21-4f2e-91b3-4a467353bcc0","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/wojtekmach/req/commit/74506ff2c5addf74df85d79dc726e9b2e264a8ba","name":"https://github.com/wojtekmach/req/commit/74506ff2c5addf74df85d79dc726e9b2e264a8ba","refsource":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-49756","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49756","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"wojtekmach","product":"req","version":"affected 0.5.3 0.6.0 semver","platforms":[]},{"source":"CNA","vendor":"wojtekmach","product":"req","version":"affected 60253dbe9436cb8e9c738f895032f2e87939b597 74506ff2c5addf74df85d79dc726e9b2e264a8ba git","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[{"source":"CNA","title":"","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 \". 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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":{"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":"<p>Sanitize attacker-influenced <tt>name</tt>, <tt>filename</tt>, and <tt>content_type</tt> values before passing them to <tt>'Elixir.Req':post/2</tt> with <tt>form_multipart:</tt>. At minimum, reject (or strip) any value containing <tt>\\r</tt>, <tt>\\n</tt>, or <tt>\"</tt>. When forwarding uploads, derive <tt>filename</tt> from a normalised string rather than <tt>Path.basename/1</tt> on a user-controlled path.</p>"}],"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 \". 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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.\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.","Type":"Description","Title":"Multipart form-data header injection in Req via unescaped name/f"}]}}}