CVE-2026-39964 TypeBot: Stored XSS via javascript: URI in text bubble links — bot author executes JS on visitors' browsers
A bot author can inject JavaScript via javascript: URIs in text bubbles, executing code in visitors' browsers to steal session tokens.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-39964?
CVE-2026-39964 is a medium-severity cross-site scripting vulnerability in baptisteArno typebot.io, published on 22 May 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
TypeBot is a chatbot builder tool. In versions prior to 3.16.0, the Typebot viewer (packages/embeds/js) renders anchor tags from rich text bubble content without filtering the javascript: URI scheme. A bot author can set a link URL to javascript:PAYLOAD, which executes in the visitor's browser context when clicked. Since the viewer is typically embedded in a third-party site, the attacker's JavaScript runs in the host page's origin and can exfiltrate cookies and session tokens. This can result in any authenticated Typebot user (including those on the free tier) being able to create a bot with this payload. Shared bots are publicly accessible — no victim authentication is required. This issue has been resolved in version 3.16.0.
Weakness: CWE-79
Which versions are affected by CVE-2026-39964?
2 open source packages ship an affected version, including @typebot.io/js.
| Package | Affected | Fixed in |
|---|---|---|
@typebot.io/js npm | All versions | 0.10.1 |
@typebot.io/js npm | All versions | 0.10.1 |
How do I fix CVE-2026-39964?
Upgrade @typebot.io/js to 0.10.1 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-39964 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39964 exists.
Sources
Also known as GHSA-hqmv-v56g-4m47.