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Fencer Intel
critical 9.1

CVE-2026-31816 in the critical feed json

Budibase Universal Auth Bypass via Webhook Query Param Injection

published 8mo ago modified 4mo ago also EUVD-2026-10358

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
16.7%
EPSS 16.7% chance of exploitation in 30 days, percentile 97%
public exploits
0
none known, plus a Nuclei check

Summary

Budibase is a low code platform for creating internal tools, workflows, and admin panels. In 3.31.4 and earlier, the Budibase server's authorized() middleware that protects every server-side API endpoint can be completely bypassed by appending a webhook path pattern to the query string of any request. The isWebhookEndpoint() function uses an unanchored regex that tests against ctx.request.url, which in Koa includes the full URL with query parameters. When the regex matches, the authorized() middleware immediately calls return next(), skipping all authentication, authorization, role checks, and CSRF protection. This means a completely unauthenticated, remote attacker can access any server-side API endpoint by simply appending ?/webhooks/trigger (or any webhook pattern variant) to the URL.

Is CVE-2026-31816 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
total
Assessed
7mo ago

Exploit prediction

16.68% chance of exploitation in the next 30 days, higher than 97% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • Nuclei template Budibase - Authentication Bypass nuclei detection template
  • github.com https://github.com/Budibase/budibase/security/advisories/GHSA-gw94-hprh-4wj8 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

  • Budibase budibase

Classification

Weakness
  • CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.