Vulnerability in Budibase
CVE-2026-42239
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.004 (29.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 30th percentile — 29.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001
Affected products
- Budibase — versions < 3.35.10
Weakness classification (CWE)
References
- github.com/Budibase/budibase/security/advisories/GHSA-4f9j-vr4p-642r (Exploit, Mitigation, Vendor Advisory)
- github.com/Budibase/budibase/releases/tag/3.35.10 (Patch, Release Notes)
Frequently asked questions
- What is CVE-2026-42239?
- CVE-2026-42239 is a high-severity vulnerability in Budibase, classified under Sensitive Cookie Without 'HttpOnly' Flag. CVSS score: 8.1/10. Published 2026-05-07.
- How severe is CVE-2026-42239?
- High severity. CVSS v3 base score is 8.1 out of 10.