{"id":65528,"date":"2026-06-24T16:59:34","date_gmt":"2026-06-24T16:59:34","guid":{"rendered":"https:\/\/zero.redgem.net\/?p=65528"},"modified":"2026-06-24T16:59:34","modified_gmt":"2026-06-24T16:59:34","slug":"appsmith-ssrf-in-rest-api-graphql-datasource-plugins-via-insufficient-host-denylist","status":"publish","type":"post","link":"https:\/\/zero.redgem.net\/?p=65528","title":{"rendered":"Appsmith: SSRF in REST API \/ GraphQL datasource plugins via insufficient host denylist_CVE-2026-55455"},"content":{"rendered":"<p>{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;Appsmith is a platform to build admin panels, internal tools, and dashboards. Prior to 2.1, the outbound HTTP host filter applied by WebClientUtils (used by the REST API and GraphQL datasource plugins) validates hosts against an exact-match string denylist. The comprehensive address-class check (loopback, any-local, link-local, fc00::\/7) exists only on a separate code path used by SMTP, not by the HTTP plugin path. As a result, an authenticated user can craft outbound requests that reach loopback-bound services inside the container. This vulnerability is fixed in 2.1.&#8221;,&#8221;published&#8221;:&#8221;2026-06-24T21:36:21.863Z&#8221;,&#8221;modified&#8221;:&#8221;2026-06-24T21:36:21.863Z&#8221;,&#8221;type&#8221;:&#8221;cve&#8221;,&#8221;title&#8221;:&#8221;Appsmith: SSRF in REST API \/ GraphQL datasource plugins via insufficient host denylist&#8221;,&#8221;source&#8221;:&#8221;GitHub_M&#8221;,&#8221;references&#8221;:&#8221;https:\/\/github.com\/appsmithorg\/appsmith\/security\/advisories\/GHSA-m23h-pvf3-2m7p&#8221;,&#8221;id&#8221;:&#8221;CVE-2026-55455&#8243;,&#8221;bulletinFamily&#8221;:&#8221;&#8221;,&#8221;cwe&#8221;:[&#8220;CWE-918&#8243;],&#8221;cvelist&#8221;:null,&#8221;sourceData&#8221;:&#8221;appsmithorg appsmith \\u003c 2.1&#8243;,&#8221;sourceHref&#8221;:&#8221;&#8221;,&#8221;cvss&#8221;:{&#8220;score&#8221;:5.3,&#8221;severity&#8221;:&#8221;MEDIUM&#8221;,&#8221;vector&#8221;:&#8221;CVSS:4.0\/AV:N\/AC:L\/AT:N\/PR:L\/UI:N\/VC:L\/VI:L\/VA:N\/SC:N\/SI:N\/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;appsmith&#8221;,&#8221;version&#8221;:&#8221;\\u003c 2.1&#8243;,&#8221;vendor&#8221;:&#8221;appsmithorg&#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;Appsmith is a platform to build admin panels, internal tools, and dashboards. Prior to 2.1, the outbound HTTP host filter applied by WebClientUtils (used by&#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":[6,8,22,12,21,13,7,11,5],"class_list":["post-65528","post","type-post","status-publish","format-standard","hentry","category-category_cve","tag-cve","tag-cvss","tag-cvss-53","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>Appsmith: SSRF in REST API \/ GraphQL datasource plugins via insufficient host denylist_CVE-2026-55455 - 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=65528\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Appsmith: SSRF in REST API \/ GraphQL datasource plugins via insufficient host denylist_CVE-2026-55455 - zero redgem\" \/>\n<meta property=\"og:description\" content=\"{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;Appsmith is a platform to build admin panels, internal tools, and dashboards. 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