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)?

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 does O3 Security protect against CVE-2026-2742?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-2742 can be triaged on real exposure rather than presence alone.

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 33th 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 August 12, 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

Aug 12, 2026

Affected

8 pkgs

Patched

8 / 8

Exploits

None indexed

Exploitation data as of Sep 22, 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 Risk0.00%

Lower risk than most CVEs33th percentile — riskier than 33% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

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`

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
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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-2742 can be triaged on real exposure rather than presence alone.

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

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

Is CVE-2026-2742 in your dependencies?

O3 Security finds CVE-2026-2742 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works