CVE-2026-41428: Budibase: Authentication Bypass via Unanchored Regex in Public Endpoint Matcher — Unauthenticated Access to Protected Endpoints

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-24 · updated 2026-06-17
Weakness: CWE-287

Description

Budibase is an open-source low-code platform. Prior to 3.35.4, the authenticated middleware uses unanchored regular expressions to match public (no-auth) endpoint patterns against ctx.request.url. Since ctx.request.url in Koa includes the query string, an attacker can access any protected endpoint by appending a public endpoint path as a query parameter. For example, POST /api/global/users/search?x=/api/system/status bypasses all authentication because the regex /api/system/status/ matches in the query string portion of the URL. This vulnerability is fixed in 3.35.4.

Affected products

budibase: before 3.35.4 — fixed in 3.35.4

How to fix

Upgrade to a fixed version: budibase 3.35.4. Check the vendor advisory for mitigations.

References

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