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CVE-2026-42239VulnerabilityPublished Updated

@budibase/backend-core · Backend core: Budibase auth session cookies are set with httpOnly:false — any XSS can lead to full account takeover

Affects @budibase/backend-coreSource GCVE Database

0
Authoritative record:CVE-2026-42239· High 8.1

Not known to be exploited · CVSS 8.1 High : upgrade to 3.35.10 soon.

Data as of 27 Oct 2026, 01:11 UTC

CVSS 3.1 base score
8.1High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 3.35.10
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 7 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade @budibase/backend-core to 3.35.10.

Affected software

ProductAffectedFixed in
npm@budibase/backend-coreAffected
  • <3.35.10
Fixed in
  • 3.35.10

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available in Budibase backend-core version 3.35.10 that sets the 'budibase:auth' cookie with httpOnly:true, secure:true, and sameSite attributes to mitigate this issue. Users should upgrade to version 3.35.10 or later to remediate the vulnerability. Until patched, mitigating XSS vulnerabilities in the application is critical, but the primary fix is to apply the official update that corrects cookie settings.

Description

Budibase backend-core sets the authentication session cookie 'budibase:auth' with httpOnly:false, allowing JavaScript access to the JWT token. This misconfiguration combined with known stored XSS vulnerabilities enables attackers to steal session tokens via XSS and achieve full account takeover. The cookie also lacks secure and sameSite flags, increasing exposure to interception and cross-site request forgery. This affects all versions prior to 3.35.10, where the issue is fixed.

References

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