{"id":56739,"date":"2026-05-25T09:42:21","date_gmt":"2026-05-25T09:42:21","guid":{"rendered":"https:\/\/zero.redgem.net\/?p=56739"},"modified":"2026-05-25T09:42:21","modified_gmt":"2026-05-25T09:42:21","slug":"crlf-injection-in-websocket-upgrade-request-in-hackney","status":"publish","type":"post","link":"https:\/\/zero.redgem.net\/?p=56739","title":{"rendered":"CRLF injection in WebSocket upgrade request in hackney_CVE-2026-47072"},"content":{"rendered":"<p>{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;Improper Neutralization of CRLF Sequences (&#8216;CRLF Injection&#8217;) vulnerability in benoitc hackney allows HTTP Request\/Response Splitting. The WebSocket upgrade code in src\/hackney_ws.erl copies the host, path, headers (ExtraHeaders), and protocols options from the caller-supplied opts map into the internal #ws_data{} record in init\/1 and then splices them verbatim into the raw HTTP\/1.1 upgrade request by binary concatenation in do_handshake\/1. No CRLF or NUL stripping is performed at any of these four injection sites. An attacker who controls any of these options \u2014 for example by forwarding URL components or header values from untrusted input into hackney_ws:start_link\/1 \u2014 can inject arbitrary HTTP headers into the outbound WebSocket upgrade request, leading to header injection, credential spoofing toward the upstream server, log and cache poisoning, or request smuggling via intermediary proxies.\\n\\nThis issue affects hackney: from 2.0.0 before 4.0.1.&#8221;,&#8221;published&#8221;:&#8221;2026-05-25T14:00:47.852Z&#8221;,&#8221;modified&#8221;:&#8221;2026-05-25T14:00:47.852Z&#8221;,&#8221;type&#8221;:&#8221;cve&#8221;,&#8221;title&#8221;:&#8221;CRLF injection in WebSocket upgrade request in hackney&#8221;,&#8221;source&#8221;:&#8221;EEF&#8221;,&#8221;references&#8221;:&#8221;https:\/\/github.com\/benoitc\/hackney\/security\/advisories\/GHSA-f9vr-g2g2-x9fg\\nhttps:\/\/cna.erlef.org\/cves\/CVE-2026-47072.html\\nhttps:\/\/osv.dev\/vulnerability\/EEF-CVE-2026-47072\\nhttps:\/\/github.com\/benoitc\/hackney\/commit\/52310ca807e7b48441ba0e9129171f535313fdd1&#8243;,&#8221;id&#8221;:&#8221;CVE-2026-47072&#8243;,&#8221;bulletinFamily&#8221;:&#8221;&#8221;,&#8221;cwe&#8221;:[&#8220;CWE-93&#8243;],&#8221;cvelist&#8221;:null,&#8221;sourceData&#8221;:&#8221;benoitc hackney 2.0.0\\nbenoitc hackney 690cecaf236fba49526da404a5bc889a24367a3e&#8221;,&#8221;sourceHref&#8221;:&#8221;&#8221;,&#8221;cvss&#8221;:{&#8220;score&#8221;:6.9,&#8221;severity&#8221;:&#8221;MEDIUM&#8221;,&#8221;vector&#8221;:&#8221;CVSS:4.0\/AV:N\/AC:L\/AT:P\/PR:N\/UI:N\/VC:N\/VI:L\/VA:N\/SC:N\/SI:H\/SA:N&#8221;,&#8221;version&#8221;:&#8221;4.0&#8243;},&#8221;cvss2&#8243;:{},&#8221;cvss3&#8243;:{&#8220;version&#8221;:&#8221;&#8221;,&#8221;vectorString&#8221;:&#8221;&#8221;,&#8221;baseScore&#8221;:0,&#8221;baseSeverity&#8221;:&#8221;&#8221;,&#8221;attackVector&#8221;:&#8221;&#8221;,&#8221;attackComplexity&#8221;:&#8221;&#8221;,&#8221;privilegesRequired&#8221;:&#8221;&#8221;,&#8221;userInteraction&#8221;:&#8221;&#8221;,&#8221;scope&#8221;:&#8221;&#8221;,&#8221;confidentialityImpact&#8221;:&#8221;&#8221;,&#8221;integrityImpact&#8221;:&#8221;&#8221;,&#8221;availabilityImpact&#8221;:&#8221;&#8221;,&#8221;cvssV3&#8243;:{&#8220;version&#8221;:&#8221;&#8221;,&#8221;vectorString&#8221;:&#8221;&#8221;,&#8221;baseScore&#8221;:0,&#8221;baseSeverity&#8221;:&#8221;&#8221;,&#8221;attackVector&#8221;:&#8221;&#8221;,&#8221;attackComplexity&#8221;:&#8221;&#8221;,&#8221;privilegesRequired&#8221;:&#8221;&#8221;,&#8221;userInteraction&#8221;:&#8221;&#8221;,&#8221;scope&#8221;:&#8221;&#8221;,&#8221;confidentialityImpact&#8221;:&#8221;&#8221;,&#8221;integrityImpact&#8221;:&#8221;&#8221;,&#8221;availabilityImpact&#8221;:&#8221;&#8221;}},&#8221;href&#8221;:&#8221;&#8221;,&#8221;category_name&#8221;:&#8221;CVE&#8221;,&#8221;post_link&#8221;:&#8221;&#8221;,&#8221;product&#8221;:&#8221;hackney&#8221;,&#8221;version&#8221;:&#8221;2.0.0&#8243;,&#8221;vendor&#8221;:&#8221;benoitc&#8221;,&#8221;ai_description&#8221;:&#8221;&#8221;,&#8221;ai_severity&#8221;:&#8221;&#8221;,&#8221;ai_vendor&#8221;:&#8221;&#8221;,&#8221;ai_product&#8221;:&#8221;&#8221;,&#8221;ai_version&#8221;:&#8221;&#8221;,&#8221;ai_score&#8221;:0}<\/p>\n","protected":false},"excerpt":{"rendered":"<p>{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;Improper Neutralization of CRLF Sequences (&#8216;CRLF Injection&#8217;) vulnerability in benoitc hackney allows HTTP Request\/Response Splitting. The WebSocket upgrade code in src\/hackney_ws.erl copies the host, path,&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[6,8,48,12,21,13,7,11,5],"class_list":["post-56739","post","type-post","status-publish","format-standard","hentry","category-category_cve","tag-cve","tag-cvss","tag-cvss-69","tag-exploit","tag-medium","tag-news","tag-security","tag-tapic","tag-vulnerability"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.5 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>CRLF injection in WebSocket upgrade request in hackney_CVE-2026-47072 - zero redgem<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/zero.redgem.net\/?p=56739\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"CRLF injection in WebSocket upgrade request in hackney_CVE-2026-47072 - zero redgem\" \/>\n<meta property=\"og:description\" content=\"{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;Improper Neutralization of CRLF Sequences (&#8216;CRLF Injection&#8217;) vulnerability in benoitc hackney allows HTTP Request\/Response Splitting. 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