GHSA-pq96-jpmf-w254 Quasar Framework: Stored/Reflected XSS via unescaped SSR meta tag rendering in getHead()

• npm quasar: < 2.22.0 → fixed in 2.22.0

Vulnerability Details File: `ui/src/utils/meta/Meta.js` — actually `ui/src/plugins/meta/Meta.js` (lines 149-176: `getAttr()` and `getHead()`) Sink: `injectServerMeta()` (same file) → `ctx.headTags += getHead(data)`, interpolated verbatim into the raw HTTP response `` by the production SSR template (`app-vite/templates/entry/ssr-prod-webserver.js` + `app-vite/lib/plugins/vite.html.js`) Entry point: the public `useMeta()` composable (`ui/src/composables/use-meta/use-meta.js`) — the single documented way apps set page title/meta/link/script tags Root Cause `getHead()` is Quasar's SSR-only serializer that turns the meta/link/script/title data collected from every `useMeta()` call into a literal HTML string, using plain template-literal interpolation with zero HTML-entity escaping and zero attribute-quote escaping: ```js function getAttr(seed) { return att => { const val = seed[att] return att + (val !== true && val !== void 0 ? `="${val}"` : '') } } function getHead(meta) { let output = '' if (meta.title) { output += `${meta.title}` } ... } ``` Contrast this with the client-side equivalent, `apply()` (same file, used only in the browser post-hydration), which builds the same tags via `document.createElement(...)` + `tag.setAttribute(att, val)` — the browser DOM API automatically escapes attribute values, so the client-side path is not vulnerable. `getHead()` is a separate, parallel implementation for the SSR case that never received the same protection. Any string containing ``, `"`, or `>` in a `title`, `meta.*.content`, `link.*.href`, or any other attribute value passed to `useMeta()` breaks out of its intended HTML context and injects arbitrary markup — including a live `` tag — directly into the raw HTML response sent to every visitor. Attack Scenario 1. A Quasar SSR application renders dynamic page metadata via the standard, documented `useMeta()` pattern — e.g. `useMeta(() => ({ title: post.title, meta: { description: { name: 'description', content: post.excerpt } } }))` for a blog/CMS/product page. 2. An attacker who can influence that underlying text (submit a blog post/comment, set their own profile display name, control a field in an integrated CMS/API) sets it to `My Postalert(document.cookie)`. 3. On every SSR render of that page — for every visitor — `getHead()` emits this payload unescaped directly into the `` of the raw HTML response. 4. The victim's browser parses the HTML top-to-bottom; the injected `` executes immediately, before hydration, with full access to `document.cookie` and the DOM. Impact • Type: CWE-79 Cross-Site Scripting • Auth required: No (attacker only needs to influence any text that reaches `useMeta()` — an extremely common pattern, e.g. blog titles, product names, user display names) • Consequence: Full client-side script execution in the victim site's origin — session/cookie theft, credential phishing overlays, account takeover, defacement. Unlike a typical XSS bug requiring a specific unusual injection point, this affects the single most common `useMeta()` use case (rendering any dynamic title/description), so it can be triggered even by ordinary content containing `&`, ` { const val = seed[att] return att + (val !== true && val !== void 0 ? `="${val}"` : '') } } function getHead(meta) { let output = '' if (meta.title) { output += `${meta.title}` } ;['meta', 'link', 'script'].forEach(type => { const metaType = meta[type] for (const att in metaType) { const attrs = Object.keys(metaType[att]) .filter(item => item !== 'innerHTML') .map(getAttr(metaType[att])) output += `` if (type === 'script') { output += (metaType[att].innerHTML || '') + '' } } }) return output } ``` Recommended Fix ```js function escapeHtml(val) { return String(val) .replaceAll('&', '&amp;') .replaceAll('', '&gt;') .replaceAll('"', '&quot;') } function getAttr(seed) { return att => { const val = seed[att] return att + (val !== true && val !== void 0 ? `="${escapeHtml(val)}"` : '') } } function getHead(meta) { let output = '' if (meta.title) { output += `${escapeHtml(meta.title)}` } // ... rest unchanged, script innerHTML intentionally left raw (JSON-LD use case) } ``` Verification Confirmed end-to-end on v2.21.1 via a local Node.js HTTP lab harness that imports the real, unmodified `Meta.js` source and reproduces the exact `useMeta()` → `injectServerMeta()` call sequence a real SSR app performs, reached via actual `curl` requests (not just isolated function calls): 1. `POST /submit` with `{"title":"My Postalert(document.cookie)","description":"\">alert(document.domain)"}` 2. `GET /render/1` returned a raw HTTP response whose `` contained: `My Postalert(document.cookie)alert(document.domain)" data-qmeta="description">` 3. Verified via `grep`: 0 occurrences of `&lt;` (nothing was escaped), 1 occurrence of a literal, unescaped `alert(...)` tag in the actual HTTP response body. A fix branch (`fix/xss-meta-tag-escaping`) is ready with the minimal patch above (adds an `escapeHtml()` helper used in `getAttr()`/`getHead()`); re-running the same PoC against the patched code shows the payload fully HTML-entity-encoded (`&lt;script&gt;...`) with no live `` tag, while normal titles containing `&` still render correctly (`&amp;`).