CVE-2026-34598

A stored and blind XSS vulnerability exists in the form title field. A malicious attacker can inject JavaScript without any authentication via a form title that is saved in the backend database. When any user visits that injected page, the JavaScript payload gets executed.

Type: Stored and Blind Cross-Site Scripting (XSS)
Affected Component: form title input field
Authentication Required: No (Unauthenticated attack possible)
Impact: Arbitrary JavaScript execution in victim’s browser

Details

A Stored XSS vulnerability occurs when an application stores malicious user input (in this case, a script injected via the form title field) in its backend database and renders it later on a page viewed by other users without proper sanitization or encoding.

In this case, the attacker can inject JavaScript payloads in the title field of a form, which the application stores in the database. When any user, such as an admin or another visitor, views the page that displays this title, the malicious script executes in their browser context.

PoC

• Visit https://yeswiki.net/?BazaR&vue=formulaire or localhost/?BazaR&vue=formulaire or
  https://ferme.yeswiki.net/[username]/?BazaR&vue=formulaire
• Click on the + icon to add a record via the Diary form.
• Inject the payload like: <script>alert(document.cookie)</script> or <script>alert(1)</script> into Name of the event and Description
• Then save the record by clicking To validate
• The payload will be executed when anyone visits /?BazaR&vue=consulter also in the diary record
  /?wiki=BazaR&vue=consulter&action=recherche&q=&id=2&facette=

The payload is persistant.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

Kodem intelligence

1. What is CVE-2026-34598? CVE-2026-34598 is a high-severity cross-site scripting (XSS) vulnerability in yeswiki/yeswiki (composer), affecting versions < 4.6.0. It is fixed in 4.6.0. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. Which versions of yeswiki/yeswiki are affected by CVE-2026-34598? yeswiki/yeswiki (composer) versions < 4.6.0 is affected.
3. Is there a fix for CVE-2026-34598? Yes. CVE-2026-34598 is fixed in 4.6.0. Upgrade to this version or later.
4. Is CVE-2026-34598 exploitable, and should I be worried? Whether CVE-2026-34598 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether CVE-2026-34598 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix CVE-2026-34598? Upgrade yeswiki/yeswiki to 4.6.0 or later.