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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS

• CVE-2026-48147: 0.11% estimated exploitation activity in the next 30 days; percentile 1.55 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The buildMatcherRegex() / matches() functions in packages/backend-core/src/middleware/matchers.ts share the same structural root cause as the recently patched CVE-2026-31816: 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. CVE-2026-31816 fixed the same unanchored-regex-on-full-URL bug in server/middleware/utils.ts but left backend-core/middleware/matchers.ts untouched. --- Details Root cause —…

Published by the source

12 Jun 2026, 18:23 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 12:55 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-wxq7-x3qp-vcr8

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-wxq7-x3qp-vcr8

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# Patch Next advisory brief: CVE-2026-48147

Advisory: Budibase: Unanchored Regex in `matchers.ts` Allows CSRF Bypass via Query String Injection in Budibase Worker
IDs: CVE-2026-48147, GHSA-wxq7-x3qp-vcr8
Record: https://patchnext.com/advisories/cve-2026-48147 (revision 2, source checked 26 Oct 2026, 12:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @budibase/backend-core 3.35.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @budibase/backend-core: affected < 3.35.4; fixed in 3.35.4

## Suggested inspection (read-only)
- `npm ls @budibase/backend-core --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @budibase/backend-core.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-wxq7-x3qp-vcr8 (OSV record GHSA-wxq7-x3qp-vcr8 lists affected ranges: npm @budibase/backend-core >=0 <3.35.4 (fixed))
- Verified: https://github.com/advisories/GHSA-wxq7-x3qp-vcr8 (GitHub-reviewed advisory GHSA-wxq7-x3qp-vcr8 lists affected ranges: npm @budibase/backend-core >=0 <3.35.4)

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