CVE-2026-2742
Fix: vaadin/flow#22998CVE-2026-2742 is a CWE-284 vulnerability in com.vaadin:flow-server. O3 Security confirms whether CVE-2026-2742 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Unauthorized session creation via reserved framework path access
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-2742.
Real-World Exposure
com.vaadin:flow-server☕com.vaadin:flow-server☕com.vaadin:flow-server☕com.vaadin:flow-server☕com.vaadin:vaadin☕com.vaadin:vaadin☕com.vaadin:vaadin☕com.vaadin:vaadinReal-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
An authentication bypass vulnerability exists in Vaadin 14.0.0 through 14.14.0, 23.0.0 through 23.6.6, 24.0.0 through 24.9.7 and 25.0.0 through 25.0.1, applications using Spring Security due to inconsistent path pattern matching of reserved framework paths.
Accessing the /VAADIN endpoint without a trailing slash bypasses security filters, and allowing unauthenticated users to trigger framework initialization and create sessions without proper authorization.
Users of affected versions using Spring Security should upgrade as follows: 14.0.0-14.14.0 upgrade to 14.14.1, 23.0.0-23.6.6 to 23.6.7, 24.0.0 - 24.9.7 to 24.9.8, and 25.0.0-25.0.1 upgrade to 25.0.2 or newer.
Please note that Vaadin versions 10-13 and 15-22 are no longer supported and you should update either to the latest 14, 23, 24, 25 version.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.vaadin:flow-server | all versions | 14.14.1 |
| ☕Maven | com.vaadin:flow-server | ≥ 23.0.0&&< 23.6.7 | 23.6.7 |
| ☕Maven | com.vaadin:flow-server | ≥ 24.0.0&&< 24.9.8 | 24.9.8 |
| ☕Maven | com.vaadin:flow-server | ≥ 25.0.0&&< 25.0.2 | 25.0.2 |
| ☕Maven | com.vaadin:vaadin | ≥ 25.0.0&&< 25.0.2 | 25.0.2 |
| ☕Maven | com.vaadin:vaadin | ≥ 24.0.0&&< 24.9.8 | 24.9.8 |
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 14.14.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-2742 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 CVE-2026-2742 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 CVE-2026-2742. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-2742 in your dependencies?
O3 detects CVE-2026-2742 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.