CVE-2026-106104 Quasar Framework: Super-linear regex backtracking on User-Agent lets one request stall a Quasar SSR server
A crafted User-Agent header causes super-linear regex backtracking in Quasar SSR, blocking the Node.js event loop and denying service to other requests.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-106104?
CVE-2026-106104 is a high-severity denial of service vulnerability in quasarframework quasar, published on 6 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Quasar Framework is a framework for building high-performance Vue.js user interfaces. Prior to 2.23.3, Platform.parseSSR() passed an unbounded User-Agent request header to getMatch() in ui/src/plugins/platform/Platform.js, whose browser-detection expressions combined greedy captures with repeated unbounded scans. Platform belongs to autoInstalledPlugins, so this parsing occurs before routing for every SSR request. A crafted unauthenticated request containing repeated version tokens without a terminating Safari token causes super-linear backtracking and blocks the Node.js event loop, delaying every other SSR request. SPA, PWA, Electron, Cordova, Capacitor, browser-extension, and static-site-generation targets are not affected because they do not parse an attacker-controlled request header through this path. This issue is fixed in version 2.23.3.
Weakness: CWE-1333
Which versions are affected by CVE-2026-106104?
2 open source packages ship an affected version, including quasar.
| Package | Affected | Fixed in |
|---|---|---|
quasar npm | All versions | 2.23.3 |
quasar npm | All versions | 2.23.3 |
How do I fix CVE-2026-106104?
Upgrade quasar to 2.23.3 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-106104 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-106104 exists.
Sources
Also known as GHSA-68jq-fhch-4xq4.