How severe is CVE-2026-2742?

No CVSS score has been assigned to CVE-2026-2742 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-2742?

CVE-2026-2742 affects the following packages: com.vaadin:flow-server (Maven), com.vaadin:flow-server (Maven), com.vaadin:flow-server (Maven), com.vaadin:flow-server (Maven), com.vaadin:vaadin (Maven), com.vaadin:vaadin (Maven), com.vaadin:vaadin (Maven), com.vaadin:vaadin (Maven). Ecosystems affected: Maven.

How do I fix CVE-2026-2742?

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.

How do I detect CVE-2026-2742 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.vaadin:flow-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-2742 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2026-2742 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-2742 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-2742?

CVE-2026-2742 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 39th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-2742?

CVE-2026-2742 is classified as CWE-284 (CWE-284). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-2742 published, and has it been updated?

CVE-2026-2742 was published on March 10, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕ Maven

Not in CISA KEV

CVE-2026-2742 — flow-server

Fix: vaadin/flow#22998

CVE-2026-2742 is a CWE-284 vulnerability in com.vaadin:flow-server. A fix is available for com.vaadin:flow-server — see the affected versions and patch details below.

Unauthorized session creation via reserved framework path access

Also known asGHSA-rjgh-wgc7-m37j

Published

Mar 10, 2026

Updated

Oct 28, 2026

Affected

8 pkgs

Patched

8 / 8

Exploits

None indexed

Exploitation data as of Nov 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

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.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk+0.04%

Lower risk than most CVEs39th percentile — riskier than 39% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

8 pkgs affected

☕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:vaadin

Real-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

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

8 total 8 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`com.vaadin:flow-server`	all versions	14.14.1`com.vaadin:flow-server:14.14.1`
☕Maven	`com.vaadin:flow-server`	≥ 23.0.0&&< 23.6.7	23.6.7`com.vaadin:flow-server:23.6.7`
☕Maven	`com.vaadin:flow-server`	≥ 24.0.0&&< 24.9.8	24.9.8`com.vaadin:flow-server:24.9.8`
☕Maven	`com.vaadin:flow-server`	≥ 25.0.0&&< 25.0.2	25.0.2`com.vaadin:flow-server:25.0.2`
☕Maven	`com.vaadin:vaadin`	≥ 25.0.0&&< 25.0.2	25.0.2`com.vaadin:vaadin:25.0.2`
☕Maven	`com.vaadin:vaadin`	≥ 24.0.0&&< 24.9.8	24.9.8`com.vaadin:vaadin:24.9.8`

Affected Products

1 product · 4 configurations

Application

vaadinvaadin

≥ 25.0.0 && < 25.0.2

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.vaadin:flow-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Workaround published by Red Hat

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Source: Red Hat security advisory for CVE-2026-2742 (CC BY 4.0)

Frequently Asked Questions

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,

O3 Security · Impact-Aware SCA

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