{"id":58401,"date":"2026-05-29T15:36:26","date_gmt":"2026-05-29T15:36:26","guid":{"rendered":"https:\/\/zero.redgem.net\/?p=58401"},"modified":"2026-05-29T15:36:26","modified_gmt":"2026-05-29T15:36:26","slug":"freescout-agent-impersonation-via-missing-hmac-verification-on-notification-reply-message-id-path","status":"publish","type":"post","link":"https:\/\/zero.redgem.net\/?p=58401","title":{"rendered":"FreeScout: Agent Impersonation via Missing HMAC Verification on Notification Reply Message-ID Path_CVE-2026-47123"},"content":{"rendered":"<p>{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;FreeScout is a free help desk and shared inbox built with PHP&#8217;s Laravel framework. Prior to 1.8.220, the email processing pipeline in FreeScout&#8217;s FetchEmails command has two code paths for identifying agent (user) replies based on In-Reply-To \/ References headers. The notification reply path (notify-{thread_id}-{user_id}-&#8230;) extracts thread_id and user_id directly from the Message-ID without HMAC verification. An external attacker who can spoof the From address of a helpdesk agent can inject messages that FreeScout processes as legitimate agent replies \u2014 which are then automatically forwarded to customers via the legitimate SMTP server. This vulnerability is fixed in 1.8.220.&#8221;,&#8221;published&#8221;:&#8221;2026-05-29T19:51:41.383Z&#8221;,&#8221;modified&#8221;:&#8221;2026-05-29T19:51:41.383Z&#8221;,&#8221;type&#8221;:&#8221;cve&#8221;,&#8221;title&#8221;:&#8221;FreeScout: Agent Impersonation via Missing HMAC Verification on Notification Reply Message-ID Path&#8221;,&#8221;source&#8221;:&#8221;GitHub_M&#8221;,&#8221;references&#8221;:&#8221;https:\/\/github.com\/freescout-help-desk\/freescout\/security\/advisories\/GHSA-6r38-6mcf-2ww3\\nhttps:\/\/github.com\/freescout-help-desk\/freescout\/commit\/d902f19038213c6a376947d269b00440908e88a0&#8243;,&#8221;id&#8221;:&#8221;CVE-2026-47123&#8243;,&#8221;bulletinFamily&#8221;:&#8221;&#8221;,&#8221;cwe&#8221;:[&#8220;CWE-290&#8243;,&#8221;CWE-345&#8243;],&#8221;cvelist&#8221;:null,&#8221;sourceData&#8221;:&#8221;freescout-help-desk freescout \\u003c 1.8.220&#8243;,&#8221;sourceHref&#8221;:&#8221;&#8221;,&#8221;cvss&#8221;:{&#8220;score&#8221;:7.5,&#8221;severity&#8221;:&#8221;HIGH&#8221;,&#8221;vector&#8221;:&#8221;CVSS:3.1\/AV:N\/AC:H\/PR:N\/UI:N\/S:C\/C:L\/I:H\/A:N&#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;freescout&#8221;,&#8221;version&#8221;:&#8221;\\u003c 1.8.220&#8243;,&#8221;vendor&#8221;:&#8221;freescout-help-desk&#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;FreeScout is a free help desk and shared inbox built with PHP&#8217;s Laravel framework. Prior to 1.8.220, the email processing pipeline in FreeScout&#8217;s FetchEmails command&#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":[6,8,16,12,15,13,7,11,5],"class_list":["post-58401","post","type-post","status-publish","format-standard","hentry","category-category_cve","tag-cve","tag-cvss","tag-cvss-75","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>FreeScout: Agent Impersonation via Missing HMAC Verification on Notification Reply Message-ID Path_CVE-2026-47123 - 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=58401\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"FreeScout: Agent Impersonation via Missing HMAC Verification on Notification Reply Message-ID Path_CVE-2026-47123 - zero redgem\" \/>\n<meta property=\"og:description\" content=\"{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;FreeScout is a free help desk and shared inbox built with PHP&#8217;s Laravel framework. 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