Vaadin Vulnerable to Authentication Bypass When Accessing the /VAADIN Endpoint Without a Trailing Slash

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

5.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L/S:N/AU:Y/R:A/V:D/RE:L/U:Amber · score source

EPSS

• CVE-2026-2742: 0.41% estimated exploitation activity in the next 30 days; percentile 35.00 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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 users should update either to the latest 14, 23, 24, 25 version.

Published by the source

10 Mar 2026, 18:31 UTC

Last modified by the source

11 Mar 2026, 19:00 UTC

Source last checked

26 Oct 2026, 16:44 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-rjgh-wgc7-m37j

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-2742

Advisory: Vaadin Vulnerable to Authentication Bypass When Accessing the /VAADIN Endpoint Without a Trailing Slash
IDs: CVE-2026-2742, GHSA-rjgh-wgc7-m37j
Record: https://patchnext.com/advisories/cve-2026-2742 (revision 1, source checked 26 Oct 2026, 16:44 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: com.vaadin:flow-server 25.0.2, 24.9.8, 23.6.7, 14.14.1; com.vaadin:vaadin 25.0.2, 24.9.8, 23.6.7, 14.14.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven com.vaadin:flow-server: affected < 14.14.1; >= 23.0.0, < 23.6.7; >= 24.0.0, < 24.9.8; >= 25.0.0, < 25.0.2; fixed in 14.14.1, 23.6.7, 25.0.2, 24.9.8
- Maven com.vaadin:vaadin: affected >= 25.0.0, < 25.0.2; >= 24.0.0, < 24.9.8; >= 23.0.0, < 23.6.7; < 14.14.1; fixed in 14.14.1, 23.6.7, 25.0.2, 24.9.8

## Suggested inspection (read-only)
- Maven com.vaadin:flow-server: check the installed version with your package manager.
- Maven com.vaadin:vaadin: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on com.vaadin:flow-server, com.vaadin:vaadin.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-rjgh-wgc7-m37j (GitHub-reviewed advisory GHSA-rjgh-wgc7-m37j lists affected ranges: Maven com.vaadin:flow-server >=0 =23.0.0 =24.0.0 =25.0.0 =25.0.0 =24.0.0 =23.0.0 =0 <14.14.1)

Commands are suggestions: review each one before running it.