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Fencer Vulns
medium 5.3

CVE-2026-2742 json

Unauthorized session creation via reserved framework path access

published 2026-03-10 8 mo ago modified 2026-09-10 1 mo ago also GHSA-rjgh-wgc7-m37j , EUVD-2026-10498

cvss
5.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits
0
none known

Summary

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.

Patch / fix

  • maven com.vaadin:flow-server 14.14.1, 23.6.7, 24.9.8, 25.0.2
  • maven com.vaadin:vaadin 14.14.1, 23.6.7, 24.9.8, 25.0.2
  • vaadin flow 25.0.1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-2742 updated cvss 6.3

com.vaadin/flow-server: Vaadin flow-server: Authentication bypass due to inconsistent path matching allows unauthorized session creation.

  • Red Hat JBoss Enterprise Application Platform 8 flow-server Red Hat JBoss Enterprise Application Platform Expansion Pack flow-server
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
8 mo ago

Exploit prediction

0.45% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 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
CNA 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:N/AU:Y/R:A/V:D/RE:L/U:Amber
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
maven com.vaadin:flow-server
<14.14.1
>=23.0.0, <23.6.7
>=24.0.0, <24.9.8
>=25.0.0, <25.0.2
14.14.1
23.6.7
24.9.8
25.0.2
maven com.vaadin:vaadin
>=25.0.0, <25.0.2
>=24.0.0, <24.9.8
>=23.0.0, <23.6.7
<14.14.1
25.0.2
24.9.8
23.6.7
14.14.1

Affected products

  • vaadin vaadin
  • vaadin flow

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.