@budibase/backend-core has potential SSRF DNS rebinding bypass in outbound fetch validation

Exploitation

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

CVSS

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

EPSS

• CVE-2026-54353: 0.21% estimated exploitation activity in the next 30 days; percentile 11.62 (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 Authenticated users with automation permissions can bypass Budibase's SSRF blacklist through DNS rebinding. The outbound fetch flow validates a hostname against the blacklist before the request is sent, but the actual socket connection later performs a separate DNS lookup through node-fetch. Since the validated IPs are never pinned to the connection, an attacker-controlled hostname can return a public IP during validation and a private/internal IP during the real connection. This results in a non-blind SSRF primitive against internal services reachable from the Budibase host, including loopback, RFC1918 ranges, and cloud metadata endpoints. Details The issue comes from the outbound fetch validation flow resolving DNS twice: During blacklist validation Again during the real socket connection The first lookup result is discarded after validation, so the second lookup is free to resolve to a different IP. This creates a classic TOCTOU DNS rebinding issue. Affected flow in:…

Published by the source

22 Jun 2026, 23:39 UTC

Last modified by the source

12 Aug 2026, 19:00 UTC

Source last checked

26 Oct 2026, 13:01 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-gfq7-5x4g-3xhf

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-gfq7-5x4g-3xhf

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# Patch Next advisory brief: CVE-2026-54353

Advisory: @budibase/backend-core has potential SSRF DNS rebinding bypass in outbound fetch validation
IDs: CVE-2026-54353, GHSA-gfq7-5x4g-3xhf
Record: https://patchnext.com/advisories/cve-2026-54353 (revision 2, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.5)
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 3.39.9. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @budibase/backend-core: affected < 3.39.9; fixed in 3.39.9

## 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-gfq7-5x4g-3xhf (OSV record GHSA-gfq7-5x4g-3xhf lists affected ranges: npm @budibase/backend-core >=0 <3.39.9 (fixed))
- Verified: https://github.com/advisories/GHSA-gfq7-5x4g-3xhf (GitHub-reviewed advisory GHSA-gfq7-5x4g-3xhf lists affected ranges: npm @budibase/backend-core >=0 <3.39.9)

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