{"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":["'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":{"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":"

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"}}},"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"}