CVE-2026-120350vaadin cross-site scripting
CVE-2026-120350 is a cross-site scripting in vaadin, rated medium (5.1 on CVSS 4.0).
Why this priority: Medium severity, with no exploitation signal.
Published · Updated · NVD status: Awaiting Analysis
What it is
Input is written into a web page without escaping, so an attacker's script runs in the browser of anyone who views it.
How it is reached
An attacker can exploit it over the network, with an ordinary user account, but someone has to act first, such as opening a file or following a link.
What an attacker gains
The scored direct impact on the component itself is low. In practice, this kind of flaw lets an attacker act inside a signed-in user's browser session. The damage can spread past the vulnerable component into others.
Is it being exploited?
There is no public report of exploitation yet.
What to do
- Apply the update for your edition of vaadin. Fixed builds: vaadin: 25.2.13, 25.3.5; vaadin-core: 25.2.13, 25.3.5; vaadin-rich-text-editor-flow: 25.2.13, 25.3.5. Other affected products have their own fixed versions on this page.
- Until it is patched, review who holds accounts that can reach it.
- Warn the people who use it, and filter files and links on the way in.
Description from NVD
The Vaadin Rich Text Editor exports a video embed without escaping its value, and then parses the resulting HTML into live DOM. A value crafted to break out of the href attribute therefore runs script in the viewer's browser. An attacker who can edit shared content pastes a video embed carrying the payload, the delta is stored, and the script runs when any user opens the page, including in read only mode.
Only content persisted through asDelta() is affected. The default HTML value, set and read through setValue and getValue, is sanitized on the server with a safelist that has no iframe, so the embed does not survive that path. Vaadin 24 and older are not affected: they build the HTML value from the editor's own innerHTML, which the browser escapes.
Users of affected versions should apply the following mitigation or upgrade. Releases that have fixed this issue include:
Product version Vaadin 25.0.0 - 25.0.13 Vaadin 25.1.0 - 25.1.13 Vaadin 25.2.0 - 25.2.12 Vaadin 25.3.0 - 25.3.4
Mitigation No fixed release on this line, upgrade to 25.2.13 or newer No fixed release on this line, upgrade to 25.2.13 or newer Upgrade to 25.2.13 Upgrade to 25.3.5
What this means for your architecture.
A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.
Components it touches
- Web front ends and single-page apps. The flaw sits between a user's browser and the web application.
- Admin consoles served to a browser. The flaw sits between a user's browser and the web application.
Trust boundaries in play
- Authenticated network access. An account is needed, so exposure follows who can sign in: customers, partners or staff.
- People who open files and links. Mail, chat and browsers are the delivery path.
- Isolation between components. The impact crosses out of the vulnerable component into others it should be isolated from.
- Between a user's browser and the web application. An attacker who crosses it can act inside a signed-in user's browser session.
Questions to answer about your own systems
- Where does vaadin run in your systems, and at which version?
- Which of those instances can be reached from the internet or partner networks?
- What can it reach once compromised: which data stores, secrets and services?
Read more
Patches and commits
More reading
Sources
- CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
- Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
- Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
- Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.