vulnerability / NVI-00014997 / Revision 1
@budibase/backend-core has potential SSRF DNS rebinding bypass in outbound fetch validation
GitHub lists this reviewed advisory for @budibase/backend-core. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
8.5 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
@budibase/backend-core
source listed< 3.39.9
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: packages/backend-core/src/utils/outboundFetch.ts ``` async function throwIfUnsafe(url: string): Promise { const parsed = parseUrl(url) if (await isBlacklisted(parsed.hostname)) { thr
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-gfq7-5x4g-3xhf ↗
GitHub Advisory Database · vendor advisory
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Public revision history
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- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.