{"id":65871,"date":"2026-06-25T13:33:46","date_gmt":"2026-06-25T13:33:46","guid":{"rendered":"https:\/\/zero.redgem.net\/?p=65871"},"modified":"2026-06-25T13:33:46","modified_gmt":"2026-06-25T13:33:46","slug":"librechat-stored-xss-via-unescaped-image-alt-text-in-markdown-artifact-preview","status":"publish","type":"post","link":"https:\/\/zero.redgem.net\/?p=65871","title":{"rendered":"LibreChat: Stored XSS via unescaped image alt text in markdown artifact preview_CVE-2026-54025"},"content":{"rendered":"<p>{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;LibreChat is an enhanced ChatGPT clone that supports multiple AI providers. Prior to 0.8.4-rc1, there is a vulnerability in LibreChat&#8217;s markdown artifact preview pipeline. The marked library v15.0.12 does not HTML-escape double-quote characters in image alt text when a custom renderer falls through to the default renderer. LibreChat&#8217;s generateMarkdownHtml function (in client\/src\/utils\/markdown.ts) installs a custom image renderer that returns false for URLs passing the isSafeUrl allowlist check, which causes marked to fall back to its built-in renderer. That built-in renderer inserts the raw alt text into the alt=\\&#8221;&#8230;\\&#8221; attribute without escaping double-quote characters. An attacker can craft an alt text such as \\&#8221; onload=\\&#8221;payload to break out of the attribute and inject an arbitrary event handler. The resulting HTML is then assigned to document.getElementById(&#8216;content&#8217;).innerHTML inside the Sandpack preview iframe, causing the payload to execute in the victim&#8217;s browser. This vulnerability is fixed in 0.8.4-rc1.&#8221;,&#8221;published&#8221;:&#8221;2026-06-25T15:53:17.026Z&#8221;,&#8221;modified&#8221;:&#8221;2026-06-25T18:02:29.089Z&#8221;,&#8221;type&#8221;:&#8221;cve&#8221;,&#8221;title&#8221;:&#8221;LibreChat: Stored XSS via unescaped image alt text in markdown artifact preview&#8221;,&#8221;source&#8221;:&#8221;GitHub_M&#8221;,&#8221;references&#8221;:&#8221;https:\/\/github.com\/danny-avila\/LibreChat\/security\/advisories\/GHSA-3phr-62qf-cxf3&#8243;,&#8221;id&#8221;:&#8221;CVE-2026-54025&#8243;,&#8221;bulletinFamily&#8221;:&#8221;&#8221;,&#8221;cwe&#8221;:[&#8220;CWE-79&#8243;],&#8221;cvelist&#8221;:null,&#8221;sourceData&#8221;:&#8221;danny-avila LibreChat \\u003c 0.8.4-rc1&#8243;,&#8221;sourceHref&#8221;:&#8221;&#8221;,&#8221;cvss&#8221;:{&#8220;score&#8221;:5.4,&#8221;severity&#8221;:&#8221;MEDIUM&#8221;,&#8221;vector&#8221;:&#8221;CVSS:3.1\/AV:N\/AC:L\/PR:L\/UI:R\/S:C\/C:L\/I:L\/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;LibreChat&#8221;,&#8221;version&#8221;:&#8221;\\u003c 0.8.4-rc1&#8243;,&#8221;vendor&#8221;:&#8221;danny-avila&#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;LibreChat is an enhanced ChatGPT clone that supports multiple AI providers. Prior to 0.8.4-rc1, there is a vulnerability in LibreChat&#8217;s markdown artifact preview pipeline. The&#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":[6,8,82,12,21,13,7,11,5],"class_list":["post-65871","post","type-post","status-publish","format-standard","hentry","category-category_cve","tag-cve","tag-cvss","tag-cvss-54","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>LibreChat: Stored XSS via unescaped image alt text in markdown artifact preview_CVE-2026-54025 - 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=65871\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"LibreChat: Stored XSS via unescaped image alt text in markdown artifact preview_CVE-2026-54025 - zero redgem\" \/>\n<meta property=\"og:description\" content=\"{&#8220;lastseen&#8221;:&#8221;&#8221;,&#8221;description&#8221;:&#8221;LibreChat is an enhanced ChatGPT clone that supports multiple AI providers. Prior to 0.8.4-rc1, there is a vulnerability in LibreChat&#8217;s markdown artifact preview pipeline. 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