Budibase: Unanchored Regex in `matchers.ts` Allows CSRF Bypass via Query String Injection in Budibase Worker

published 2026-05-27 5 mo ago modified 2026-09-10 1 mo ago also GHSA-wxq7-x3qp-vcr8 , EUVD-2026-32606

cvss: 6.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.1%; EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits: 0; none known

Budibase is an open-source low-code platform. Prior to 3.35.4, the buildMatcherRegex() / matches() functions in packages/backend-core/src/middleware/matchers.ts route patterns are compiled into unanchored regular expressions and tested against ctx.request.url, which includes the full query string. The CSRF middleware in the Budibase Worker uses this matching system to decide whether to skip CSRF token validation. An unauthenticated attacker can forge state-changing cross-origin requests against any Worker API endpoint by injecting a public route pattern into the query string, causing the CSRF middleware to skip token validation entirely. This allows actions such as sending admin invites, modifying global configuration, and managing users without a valid CSRF token. This vulnerability is fixed in 3.35.4.

Patch / fix

fixed in 1

npm @budibase/backend-core 3.35.4

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 5 mo ago (2026-05-27)

Exploit prediction

0.11% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/Budibase/budibase/security/advisories/GHSA-wxq7-x3qp-vcr8 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
GitHub	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

Affected packages

ecosystem	package	affected	fixed in
npm	@budibase/backend-core	<3.35.4	3.35.4

Affected products

Budibase budibase

Classification

Weakness

CWE-185 Incorrect Regular Expression
CWE-352 Cross-Site Request Forgery

References

github.com /Budibase/budibase/security/advisories/GHSA-wxq7-x3qp-vcr8
exploit, web
nvd.nist.gov /vuln/detail/CVE-2026-48147
advisory
github.com /Budibase/budibase
package

Sources

Fencer Vulns 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.

Summary