{"id":66277,"date":"2026-06-26T14:18:02","date_gmt":"2026-06-26T14:18:02","guid":{"rendered":"https:\/\/zero.redgem.net\/?p=66277"},"modified":"2026-06-26T14:18:02","modified_gmt":"2026-06-26T14:18:02","slug":"envoy-null-pointer-deref-in-internal-redirects","status":"publish","type":"post","link":"https:\/\/zero.redgem.net\/?p=66277","title":{"rendered":"Envoy: Null pointer deref in internal redirects_CVE-2026-47221"},"content":{"rendered":"<p>{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.18.0 until 1.35.13, 1.36.9, 1.37.5, and 1.38.3, the router filter contains a null pointer dereference vulnerability when handling HTTP 303 (See Other) internal redirects for body-less non-GET\/HEAD requests. When a POST, PUT, DELETE, or PATCH request without a body is sent to a route configured with internal redirect policy that includes 303 in redirect_response_codes, and the upstream responds with HTTP 303, the redirect handling code attempts to drain a request body buffer that was never allocated. This results in a segmentation fault that crashes the entire Envoy process. When route configured with internal_redirect_policy including 303 in redirect_response_codes and upstream must return HTTP 303 response, an unauthenticated attacker can exploit this to cause complete denial of service, terminating all active connections. This vulnerability is fixed in 1.35.13, 1.36.9, 1.37.5, and 1.38.3.&#8221;,&#8221;published&#8221;:&#8221;2026-06-26T17:35:29.518Z&#8221;,&#8221;modified&#8221;:&#8221;2026-06-26T18:33:34.507Z&#8221;,&#8221;type&#8221;:&#8221;cve&#8221;,&#8221;title&#8221;:&#8221;Envoy: Null pointer deref in internal redirects&#8221;,&#8221;source&#8221;:&#8221;GitHub_M&#8221;,&#8221;references&#8221;:&#8221;https:\/\/github.com\/envoyproxy\/envoy\/security\/advisories\/GHSA-rcff-gw58-pjpr&#8221;,&#8221;id&#8221;:&#8221;CVE-2026-47221&#8243;,&#8221;bulletinFamily&#8221;:&#8221;&#8221;,&#8221;cwe&#8221;:[&#8220;CWE-476&#8243;],&#8221;cvelist&#8221;:null,&#8221;sourceData&#8221;:&#8221;envoyproxy envoy \\u003e= 1.38.0, \\u003c 1.38.3\\nenvoyproxy envoy \\u003e= 1.37.0, \\u003c 1.37.5\\nenvoyproxy envoy \\u003e= 1.36.0, \\u003c 1.36.9\\nenvoyproxy envoy \\u003e= 1.18.0, \\u003c 1.35.13&#8243;,&#8221;sourceHref&#8221;:&#8221;&#8221;,&#8221;cvss&#8221;:{&#8220;score&#8221;:5.9,&#8221;severity&#8221;:&#8221;MEDIUM&#8221;,&#8221;vector&#8221;:&#8221;CVSS:3.1\/AV:N\/AC:H\/PR:N\/UI:N\/S:U\/C:N\/I:N\/A:H&#8221;,&#8221;version&#8221;:&#8221;3.1&#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;envoy&#8221;,&#8221;version&#8221;:&#8221;\\u003e= 1.38.0, \\u003c 1.38.3&#8243;,&#8221;vendor&#8221;:&#8221;envoyproxy&#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;Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.18.0 until 1.35.13, 1.36.9, 1.37.5, and 1.38.3, the router filter contains&#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":[6,8,97,12,21,13,7,11,5],"class_list":["post-66277","post","type-post","status-publish","format-standard","hentry","category-category_cve","tag-cve","tag-cvss","tag-cvss-59","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>Envoy: Null pointer deref in internal redirects_CVE-2026-47221 - 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=66277\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Envoy: Null pointer deref in internal redirects_CVE-2026-47221 - zero redgem\" \/>\n<meta property=\"og:description\" content=\"{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;Envoy is an open source edge and service proxy designed for cloud-native applications. 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