# 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.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Oct 2026
- **Updated:** 9 Oct 2026
- **Also known as:** GHSA-68jq-fhch-4xq4

## 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 (Inefficient Regular Expression Complexity)

## Which versions are affected by CVE-2026-106104?

2 open source packages ship an affected version, including quasar.


| Package | Ecosystem | 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.

## Is CVE-2026-106104 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-106104 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-106104 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-106104 exists.

Affected packages and fixed versions:
- quasar (npm): affected all versions; fixed in 2.23.3
- quasar (npm): affected all versions; fixed in 2.23.3

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-106104/ (Markdown: https://insights.sbomify.com/CVE-2026-106104/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-106104
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-106104
- OSV: https://osv.dev/vulnerability/CVE-2026-106104

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-106104/
Summaries are generated and may contain mistakes; the official description above is the record.