---
id: 2026-10-sentry-nextjs-tunnelroute-middleware-bypass-cve-2026-114139-dompurify-ghsa-cg2g-xh64-v4q7
title: "@sentry/nextjs tunnelRoute lets requests skip Next.js middleware (CVE-2026-114139, 9.1, webpack builds) and DOMPurify 3.4.4 to 3.4.16 sanitizer bypass (GHSA-cg2g-xh64-v4q7, 9.2)"
date_disclosed: 2026-10-22
date_fixed: 2026-10-22
last_updated: 2026-10-26
severity: critical
status: patched
ecosystems: [npm, nextjs, react]
tools_affected: ["@sentry/nextjs 9.36.0 before 9.47.2, 10.0.0-alpha.0 before 10.75.2, 11.0.0-alpha.0 before 11.0.0-rc.1 with tunnelRoute and a webpack build", "dompurify 3.4.4 through 3.4.16"]
tags: [cve, ghsa, nextjs, sentry, middleware-bypass, auth-bypass, tunnelroute, webpack, dompurify, xss, sanitizer-bypass, npm]
---

## TL;DR
Two Critical records on 2026-10-22 and 10-23 hit packages that sit in most vibe-coded Next.js apps. **@sentry/nextjs** with `tunnelRoute` set rewrote matching requests before Next.js middleware ran, so a request shaped like a tunnel path reached the rest of the app without auth middleware; webpack builds only (the Turbopack path was not affected); fixed 9.47.2, 10.75.2 and 11.0.0-rc.1 (CVE-2026-114139 / GHSA-mchm-gjx6-7h55, CVSS 4.0 9.1). **DOMPurify** 3.4.4 through 3.4.16 let crafted markup through the sanitizer and into the DOM as script-capable content; fixed 3.4.17 (GHSA-cg2g-xh64-v4q7, 9.2). Upgrade both; if the Sentry tunnel was on in a webpack build, review access logs for tunnel-prefixed paths that reached protected routes.

## What happened

**@sentry/nextjs.** GitHub Advisory Database published 2026-10-22, reviewed 10-23, CWE-863. The SDK's `tunnelRoute` option proxies browser-side Sentry events through the app to avoid ad blockers; the SDK implemented it as a rewrite rule that ran before middleware. A request matching the tunnel pattern was therefore rewritten and never evaluated by `middleware.ts`, which is where Clerk, NextAuth and Supabase guards live in a typical app. Three fixed lines: 9.47.2, 10.75.2, 11.0.0-rc.1; the record scopes the bug to webpack builds and says Turbopack users are not affected. Registry 2026-10-26: `@sentry/nextjs` latest 11.9.0. Companion entry for the same class, auth enforced only in middleware that a request can skip: [Clerk SDK middleware bypass batch](2026-04-clerk-sdk-middleware-bypass-cve-batch.md).

**DOMPurify.** Published 2026-10-23, Critical 9.2, affected `>= 3.4.4, <= 3.4.16`, patched 3.4.17. The advisory text is internally inconsistent: one paragraph says the bypass needs a non-default configuration and another says default settings are affected; this file carries both statements rather than resolving them. Registry 2026-10-26: `dompurify` latest 3.4.17. DOMPurify sits under `isomorphic-dompurify`, most Markdown renderers and several rich-text editors, so `npm ls dompurify` matters more than a direct dependency check.

Why it is here: an AI-generated Next.js app almost always has Sentry's wizard output in `next.config.js` with `tunnelRoute` set, and the middleware file is the whole auth layer.

## Am I affected?

- `npm ls @sentry/nextjs dompurify`; `grep -rn tunnelRoute next.config.*`; `next build` output says `webpack` or `Turbopack`.
- A webpack build with `tunnelRoute` on any affected version and any middleware-enforced route: review request logs for paths carrying the tunnel prefix that returned 200 from protected handlers.

## If you are affected

1. Upgrade @sentry/nextjs to 9.47.2 / 10.75.2 / 11.0.0-rc.1 or later and dompurify to 3.4.17; rebuild and redeploy.
2. Until the upgrade, remove `tunnelRoute` from the Sentry config (events go direct to Sentry).
3. If logs show the bypass used, follow [if your web app was compromised](../playbooks/if-your-webapp-was-compromised.md).

## Prevention

- [Auditing a vibe-coded repo](../playbooks/auditing-a-vibe-coded-repo.md): auth enforced in route handlers and data layer too, never only in middleware.
- [npm hardening](../prevention/npm-hardening.md): lockfile audit on every deploy; transitive `dompurify` pins.

## Sources
- [GitHub Advisory Database — GHSA-mchm-gjx6-7h55](https://github.com/advisories/GHSA-mchm-gjx6-7h55) — fetched 2026-10-26: CVE-2026-114139, 9.1 and vector, the three ranges, the webpack scope and Turbopack note, CWE-863.
- [GitHub Advisory Database — GHSA-cg2g-xh64-v4q7](https://github.com/advisories/GHSA-cg2g-xh64-v4q7) — fetched 2026-10-26: 9.2, range 3.4.4 to 3.4.16, patched 3.4.17, the two configuration statements.
- [GitHub Advisory Database — reviewed Critical `npm` listing](https://github.com/advisories?query=type%3Areviewed+severity%3Acritical+ecosystem%3Anpm) — fetched 2026-10-26: both rows with dates.
- npm registry (`npm view @sentry/nextjs version`, `npm view dompurify version`) — run 2026-10-26: 11.9.0 and 3.4.17.