React Router (and Remix v1/v2) SPA open navigation redirects originating from loaders or actions in Framework Mode, Data Mode, or the unstable RSC modes can result in unsafe URLs causing unintended javascript execution on the client. This is only an issue if developers are creating redirect paths from untrusted content or via an open redirect.

[!NOTE] This does not impact applications that use Declarative Mode (<BrowserRouter>).

Summary The current implementation of striphtml can cause an infinite loop when the input string contains <, has at least one character before <, and no > appears after <.

Details The problem is in src/filters/html.ts. Specifically, the following part has the infinite loop.

// Raw-text blocks (HTML5) plus '<...>' as the catch-all kind; a regex // equivalent is O(n^2) in V8 on unclosed openers. export function striphtml (this: FilterImpl, v: string) { const str = stringify(v) this.context.memoryLimit.use(str.length) const blocks = new Map([['<script', '</script>'], ['<style', '</style>'], ['<!--', '-->'], ['<', '>']]) let out = '' let i = 0 while (i < str.length) { const lt = str.indexOf('<', i) if (lt < 0) return out + str.slice(i) out += str.slice(i, lt) for (const [opener, closer] of blocks) { if (!str.startsWith(opener, lt)) continue const e = str.indexOf(closer, lt + opener.length) if (e >= 0) { i = e + closer.length; break } blocks.delete(opener) } if (i === lt) return out + str.slice(lt) } return out }

For the input "a<", the variable lt is updated to 1 by const lt = str.indexOf('<', i). However, the variable i is never updated from its initial value of 0. This is because in const e = str.indexOf(closer, lt + opener.length), e becomes -1, since there is no > after <. Therefore, when execution reaches if (i === lt) return out + str.slice(lt), i is 0. This is the same state as at the beginning of the loop. As a result, the same thing is repeated again from that state, causing an infinite loop.

PoC const { Liquid } = require('liquidjs');

const engine = new Liquid();

engine.parseAndRender('{{ html | striphtml }}', { html: 'a<' }).then(console.log);

console.log("This is never displayed.");

Impact This is an infinite loop vulnerability (cf. https://cwe.mitre.org/data/definitions/835.html). This results in a denial of service (DoS). Although a ReDoS vulnerability has previously been reported in the affected function (cf. https://github.com/harttle/liquidjs/security/advisories/GHSA-r7g9-xpmj-5fcq), this issue can cause a more severe impact than that ReDoS vulnerability with an input of only two characters at minimum.

Recommended Fix There is an issue with the following conditional branch.

if (i === lt) return out + str.slice(lt);

The following should fix the issue.

if (i <= lt) return out + str.slice(lt);

React Router is a router for React. In versions 7.0.0 through 7.14.1, when using Framework Mode, a combination of steps could potentially allow unauthorized remote code execution (RCE) through external requests. This attack requires the application code to have an existing prototype pollution vulnerability, which can then be leveraged in a 2-step attack where the second step triggers unauthorized RCE on the remote server. This does not impact applications using Declarative Mode (<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>). This is patched in version 7.14.2.

React Router is a router for React. In versions 7.7.0 through 7.13.1, when using React Router's unstable React Server Components (RSC) APIs, there is a potential client-side Cross-Site Scripting (XSS) vulnerability in the RSC redirect handling if redirects come from untrusted sources. This does not impact applications that are not using the unstable RSC APIs in React Router. This is patched in version 7.13.2.

A DoS vulnerability exists in the React Router v7 Framework Mode, as well as Remix v2.9.0+ with Single Fetch enabled. In some scenarios the underlying serialization algorithm can become a bottleneck when encoding specific types of data into server responses. Please upgrade to React Router v7.14.0 or later.

[!NOTE] This does not impact your React Router application if you are using Declarative Mode (<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>).

Certain URLs passed to the redirect function can trigger an open redirect to an external domain depending on the level of validation done by the application prior to returning the redirect.

[!NOTE] This does not impact your React Router application if you are using Declarative Mode (<BrowserRouter>)

React Router is a router for React. In versions 7.0.0 through 7.14.x of react-router and versions 2.10.0 through 2.17.4 of @remix-run/server-runtime, certain crafted requests can consume disproportionate server resources via unbounded path expansion in the manifest endpoint, resulting in response time degradation and/or service unavailability for end users. This affects React Router Framework Mode applications as well as Remix applications. This does not impact applications using Declarative Mode (<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>). This is patched in react-router version 7.15.0 and @remix-run/server-runtime version 2.17.5.

A XSS vulnerability exists in in React Router's <ScrollRestoration> API in Framework Mode when using the getKey/storageKey props during Server-Side Rendering which could allow arbitrary JavaScript execution during SSR if untrusted content is used to generate the keys.

[!NOTE] This does not impact applications if developers have disabled server-side rendering in Framework Mode, or if they are using Declarative Mode (<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>).

Applications with open redirects could permit attacker crafted links to result in redirects to unexpected external location or XSS vectors.

If application code allows attacker supplied input to overwrite certain aspects of errors caught by the SSR process, then it was possible for attacker to trigger unexpected constructor execution on the client which would trigger outbound network traffic. This is only possible with very specific (and unlikely) application layer code.

[!NOTE] This does not impact your application if you are using Declarative Mode. This only impacts Framework Mode and Data Mode applications doing manual SSR/hydration

React Router is a router for React. In versions 7.11.0 through 7.17.0, the RSCErrorHandler is missing protocol validation, allowing for redirects from untrusted sources. This issue is a follow up to CVE-2026-53667, and only affects consuming applications if they are using the unstable RSC APIs. This issue has been fixed in version 7.18.0.

React Router is a router for React. Versions 6.0.0 through 7.17.0 are vulnerable to Open Redirtect through use of backslashes in <Link> and useNavigate. This issue is a follow up to CVE-2025-68470 and has been fixed in version 7.18.0.

React Router is a router for React. In versions 7.0.0 through 7.17.0, the manifest endpoint could be accessed via unauthenticated targeted requests that would put heavy load on the server and slow down response times. This issue is a follow up to CVE-2026-42342, and does not does not impact React Router applications using Declarative Mode (<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>). This issue has been fixed in version 7.18.0.

Tophat is a mobile applications testing harness. Prior to 2.5.1, Tophat is affected by remote code execution via crafted tophat:// or http://localhost:29070 URLs. The arguments query parameter flows unsanitized from URL parsing through to /bin/bash -c execution, allowing an attacker to execute arbitrary commands on a developer's macOS workstation. Any developer with Tophat installed is vulnerable. For previously trusted build hosts, no confirmation dialog appears. Attacker commands run with the user's permissions. This vulnerability is fixed in 2.5.1.

React Router is a router for React. In versions 7.5.1 through 7.13.1, when using Framework Mode with pre-rendering enabled, improper neutralization of the HTTP Location header value can permit Cross-Site Scripting (XSS) in the statically generated HTML files if the redirect location comes from an untrusted source. This does not impact applications using Declarative Mode (<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>). This is patched in version 7.13.2.

A XSS vulnerability exists in in React Router's meta()/<Meta> APIs in Framework Mode when generating script:ld+json tags which could allow arbitrary JavaScript execution during SSR if untrusted content is used to generate the tag.

[!NOTE] This does not impact applications using Declarative Mode (<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>).

If applications use createFileSessionStorage() from @react-router/node (or @remix-run/node/@remix-run/deno in Remix v2) with an unsigned cookie, it is possible for an attacker to cause the session to try to read/write from a location outside the specified session file directory. The success of the attack would depend on the permissions of the web server process to access those files.

Read files cannot be returned directly to the attacker. Session file reads would only succeed if the file matched the expected session file format. If the file matched the session file format, the data would be populated into the server side session but not directly returned to the attacker unless the application logic returned specific session information.

An attacker-supplied path can be crafted so that when a React Router application navigates to it via navigate(), <Link>, or redirect(), the app performs a navigation/redirect to an external URL. This is only an issue if developers pass untrusted content into navigation paths in their application code.

Summary

The rubyLsp.branch VS Code workspace setting was interpolated without sanitization into a generated Gemfile, allowing arbitrary Ruby code execution when a user opens a project containing a malicious .vscode/settings.json.

Other editors that support workspace setting that get automatically applied upon opening the editor and trusting the workspace are also impacted since the server is the component that performs the interpolation.

Details

The branch CLI argument passed to the ruby-lsp server was interpolated in the generated .ruby-lsp/Gemfile without sanitization. Editors that allow defining settings saved at the workspace level (e.g.: .vscode/settings.json) that gets automatically applied open the possibility to craft a malicious repository that once opened and trusted in the editor would run arbitrary code.

Impact

Code execution with the privileges of the user who opens the malicious project. Ruby LSP assumes workspace code is trusted and so opening the editor on an untrusted workspace can lead to executing potentially dangerous code.

Remediation

The rubyLsp.branch setting has been removed entirely. VS Code extensions auto-update by default, so most users will receive the fix without action. Users who have disabled auto-updates should update to extension version >= 0.10.2.

The branch CLI flag was also entirely removed from the ruby-lsp gem. For users that don't add ruby-lsp to their Gemfiles, the server should auto-update. Users with the ruby-lsp in the Gemfile and locked to a specific version should update to >= 0.26.9.

React Router (or Remix v2) is vulnerable to CSRF attacks on document POST requests to UI routes when using server-side route action handlers in Framework Mode, or when using React Server Actions in the new unstable RSC modes.

[!NOTE] This does not impact applications that use Declarative Mode (<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>).

A cross-site scripting (XSS) vulnerability in Smart Search & Filter Shopify and BigCommerce apps allows a remote attacker to execute arbitrary JavaScript in the web browser of a user, by including a malicious payload into several filter parameter

Hydrogen is a React-based framework for building dynamic, Shopify-powered custom storefronts. There is a potential Cross-Site Scripting (XSS) vulnerability where an arbitrary user is able to execute scripts on pages that are built with Hydrogen. This affects all versions of Hydrogen starting from version 0.10.0 to 0.18.0. This vulnerability is exploitable in applications whose hydrating data is user controlled. All Hydrogen users should upgrade their project to version 0.19.0. There is no current workaround, and users should update as soon as possible. Additionally, the Content Security Policy is not an effective mitigation for this vulnerability.

A cross-site scripting vulnerability exists in koa-shopify-auth v3.1.61-v3.1.62 that allows an attacker to inject JS payloads into the shop parameter on the /shopify/auth/enablecookies endpoint.