{"id":53033,"date":"2026-05-11T12:35:36","date_gmt":"2026-05-11T12:35:36","guid":{"rendered":"https:\/\/zero.redgem.net\/?p=53033"},"modified":"2026-05-11T12:35:36","modified_gmt":"2026-05-11T12:35:36","slug":"zen-browser-mar-updater-ships-with-signature-verification-removed-unsigned-updates-accepted","status":"publish","type":"post","link":"https:\/\/zero.redgem.net\/?p=53033","title":{"rendered":"Zen Browser MAR updater ships with signature verification removed \u2014 unsigned updates accepted_CVE-2026-41431"},"content":{"rendered":"<p>{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;Zen is a firefox-based browser. Prior to 1.19.9b, Zen Browser ships a Mozilla Application Resource (MAR) updater (org.mozilla.updater) that has had all MAR signature verification stripped from the Firefox codebase it was forked from. The MAR files served to users contain zero cryptographic signatures, and the updater binary contains zero cryptographic verification code. This eliminates the defense-in-depth that MAR signing provides. If the update server or GitHub release pipeline is compromised, arbitrary unsigned code can be delivered to all Zen users via the auto-update mechanism. This vulnerability is fixed in 1.19.9b.&#8221;,&#8221;published&#8221;:&#8221;2026-05-11T16:55:10.814Z&#8221;,&#8221;modified&#8221;:&#8221;2026-05-11T16:55:10.814Z&#8221;,&#8221;type&#8221;:&#8221;cve&#8221;,&#8221;title&#8221;:&#8221;Zen Browser MAR updater ships with signature verification removed \u2014 unsigned updates accepted&#8221;,&#8221;source&#8221;:&#8221;GitHub_M&#8221;,&#8221;references&#8221;:&#8221;https:\/\/github.com\/zen-browser\/desktop\/security\/advisories\/GHSA-qpj9-m8jc-mw6q\\nhttps:\/\/github.com\/zen-browser\/desktop\/commit\/270db6d6713d2c6c14d9df0b4bc7662843d3d54e&#8221;,&#8221;id&#8221;:&#8221;CVE-2026-41431&#8243;,&#8221;bulletinFamily&#8221;:&#8221;&#8221;,&#8221;cwe&#8221;:[&#8220;CWE-347&#8243;],&#8221;cvelist&#8221;:null,&#8221;sourceData&#8221;:&#8221;zen-browser desktop \\u003c 1.19.9b&#8221;,&#8221;sourceHref&#8221;:&#8221;&#8221;,&#8221;cvss&#8221;:{&#8220;score&#8221;:8,&#8221;severity&#8221;:&#8221;HIGH&#8221;,&#8221;vector&#8221;:&#8221;CVSS:3.1\/AV:N\/AC:H\/PR:H\/UI:N\/S:C\/C:H\/I:H\/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;desktop&#8221;,&#8221;version&#8221;:&#8221;\\u003c 1.19.9b&#8221;,&#8221;vendor&#8221;:&#8221;zen-browser&#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;Zen is a firefox-based browser. Prior to 1.19.9b, Zen Browser ships a Mozilla Application Resource (MAR) updater (org.mozilla.updater) that has had all MAR signature verification&#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":[6,8,83,12,15,13,7,11,5],"class_list":["post-53033","post","type-post","status-publish","format-standard","hentry","category-category_cve","tag-cve","tag-cvss","tag-cvss-80","tag-exploit","tag-high","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>Zen Browser MAR updater ships with signature verification removed \u2014 unsigned updates accepted_CVE-2026-41431 - 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=53033\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Zen Browser MAR updater ships with signature verification removed \u2014 unsigned updates accepted_CVE-2026-41431 - zero redgem\" \/>\n<meta property=\"og:description\" content=\"{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;Zen is a firefox-based browser. 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