CVE-2026-42239 Budibase auth session cookies are set with httpOnly:false — any XSS can lead to full account takeover
Attackers can steal session cookies via XSS due to missing httpOnly flag, leading to full account takeover in Budibase.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-42239?
CVE-2026-42239 is a high-severity vulnerability in budibase, published on 7 May 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Official description
Budibase is an open-source low-code platform. Prior to version 3.35.10, the budibase:auth cookie containing the JWT session token is set with httpOnly: false at packages/backend-core/src/utils/utils.ts:218. JavaScript can read this cookie via document.cookie. This means every XSS becomes a full account takeover — the attacker steals the JWT and has persistent access to the victim's account. The cookie also lacks secure: true (sent over plaintext HTTP) and sameSite attribute. This issue has been patched in version 3.35.10.
Weakness: CWE-1004
Which versions are affected by CVE-2026-42239?
2 open source packages ship an affected version, including @budibase/backend-core. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
@budibase/backend-core npm | All versions | 3.35.10 |
@budibase/backend-core npm | All versions | 3.35.10 |
Products include Budibase Budibase.
How do I fix CVE-2026-42239?
Upgrade @budibase/backend-core to 3.35.10 or later.
Is CVE-2026-42239 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42239 exists.
Other vulnerabilities in budibase
- CVE-2026-54350 Budibase: Anonymous NoSQL operator injection via published-app query templates
- CVE-2026-27702 Budibase Vulnerable to Remote Code Execution via Unsafe eval() in View Filter Map Function (Budibase Cloud)
- CVE-2026-54352 Budibase: Arbitrary file read by workspace-builder via PWA-zip symlink upload
- CVE-2026-31818 Budibase: Server-Side Request Forgery via REST Connector with Empty Default Blacklist
- CVE-2026-30240 Budibase PWA ZIP Upload Path Traversal Allows Reading Arbitrary Server Files Including All Environment Secrets
Sources
Also known as GHSA-4f9j-vr4p-642r.