Svelte performance oriented web framework. Prior to version 5.53.5, the contents of `bind:innerText` and `bind:textContent` on `contenteditable` elements were not properly escaped. This could enable HTML injection and Cross-Site Scripting (XSS) if rendering untrusted data as the binding's initial value on the server. Version 5.53.5 fixes the issue.

svelte performance oriented web framework. From 5.39.3, <=5.51.4, in certain circumstances, the server-side rendering output of an <option> element does not properly escape its content, potentially allowing HTML injection in the SSR output. Client-side rendering is not affected. This vulnerability is fixed in 5.51.5.

svelte performance oriented web framework. Versions of svelte prior to 5.51.5 are vulnerable to cross-site scripting (XSS) during server-side rendering. When using spread syntax to render attributes from untrusted data, event handler properties are included in the rendered HTML output. If an application spreads user-controlled or external data as element attributes, an attacker can inject malicious event handlers that execute in victims' browsers. This vulnerability is fixed in 5.51.5.

svelte performance oriented web framework. Prior to 5.51.5, when using <svelte:element this={tag}> in server-side rendering, the provided tag name is not validated or sanitized before being emitted into the HTML output. If the tag string contains unexpected characters, it can result in HTML injection in the SSR output. Client-side rendering is not affected. This vulnerability is fixed in 5.51.5.

SvelteKit is a framework for rapidly developing robust, performant web applications using Svelte. "Unsanitized input from *the request URL* flows into `end`, where it is used to render an HTML page returned to the user. This may result in a Cross-Site Scripting attack (XSS)." The files `packages/kit/src/exports/vite/dev/index.js` and `packages/kit/src/exports/vite/utils.js` both contain user controllable data which under specific conditions may flow to dev mode pages. There is little to no expected impact. The Vite development is not exposed to the network by default and even if someone were able to trick a developer into executing an XSS against themselves, a development database should not have any sensitive data. None the less this issue has been addressed in version 2.8.3 and all users are advised to upgrade.

SvelteKit is a framework for rapidly developing robust, performant web applications using Svelte. The static error.html template for errors contains placeholders that are replaced without escaping the content first. error.html is the page that is rendered when everything else fails. It can contain the following placeholders: %sveltekit.status% — the HTTP status, and %sveltekit.error.message% — the error message. This leads to possible injection if an app explicitly creates an error with a message that contains user controlled content. Only applications where user provided input is used in the `Error` message will be vulnerable, so the vast majority of applications will not be vulnerable This issue has been addressed in version 2.8.3 and all users are advised to upgrade. There are no known workarounds for this vulnerability.

SvelteKit is a framework for rapidly developing robust, performant web applications using Svelte. Prior to 2.20.6 , unsanitized search param names cause XSS vulnerability. You are affected if you iterate over all entries of event.url.searchParams inside a server load function. Attackers can exploit it by crafting a malicious URL and getting a user to click a link with said URL. This vulnerability is fixed in 2.20.6.

svelte performance oriented web framework. A potential mXSS vulnerability exists in Svelte for versions up to but not including 4.2.19. Svelte improperly escapes HTML on server-side rendering. The assumption is that attributes will always stay as such, but in some situation the final DOM tree rendered on browsers is different from what Svelte expects on server-side rendering. This may be leveraged to perform XSS attacks, and a type of the XSS is known as mXSS (mutation XSS). More specifically, this can occur when injecting malicious content into an attribute within a `noscript` tag. This issue has been addressed in release version 4.2.19. Users are advised to upgrade. There are no known workarounds for this vulnerability.