GHSA-xwg3-qrcg-w9x6 is a medium-severity (CVSS 4) CWE-208 vulnerability in com.vaadin:flow-server. O3 Security confirms whether GHSA-xwg3-qrcg-w9x6 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Timing side channel vulnerability in UIDL request handler in Vaadin 10, 11-14, and 15-18
Real-World Exposure
com.vaadin:flow-server☕com.vaadin:flow-server☕com.vaadin:flow-serverReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Non-constant-time comparison of CSRF tokens in UIDL request handler in com.vaadin:flow-server versions 1.0.0 through 1.0.13 (Vaadin 10.0.0 through 10.0.16), 1.1.0 prior to 2.0.0 (Vaadin 11 through 13), 2.0.0 through 2.4.6 (Vaadin 14.0.0 through 14.4.6), 3.0.0 prior to 5.0.0 (Vaadin 15 prior to 18), and 5.0.0 through 5.0.2 (Vaadin 18.0.0 through 18.0.5) allows attacker to guess a security token via timing attack.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.vaadin:flow-server | ≥ 1.0.0&&< 1.0.14 | 1.0.14 |
| ☕Maven | com.vaadin:flow-server | ≥ 1.1.0&&< 2.4.7 | 2.4.7 |
| ☕Maven | com.vaadin:flow-server | ≥ 3.0.0&&< 5.0.3 | 5.0.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.vaadin:flow-server. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update com.vaadin:flow-server to 1.0.14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xwg3-qrcg-w9x6 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-xwg3-qrcg-w9x6 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-xwg3-qrcg-w9x6. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-xwg3-qrcg-w9x6 in your dependencies?
O3 detects GHSA-xwg3-qrcg-w9x6 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.