---
title: "CVE-2026-31818: Budibase: Server-Side Request Forgery via REST Connector with Empty Default Blacklist"
url: https://erroneo.us/security/cve/CVE-2026-31818/
description: "CVE-2026-31818 (@budibase/backend-core (npm)): Budibase is an open-source low-code platform. Prior to version 3.33.4, a server-side request forgery (SSRF)…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-04-03
date_modified: 2026-04-03
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-31818"
kev: false
cvss: 9.6
epss: 0.00434
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-31818: Budibase: Server-Side Request Forgery via REST Connector with Empty Default Blacklist

**Signal:** Critical, preconditions apply. Severe if exploited, but exploitation needs conditions that may not apply to you. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.4% , percentile 37: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 37% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Needs an account (low (any account)). Exposure depends on who can log in.
- Only applies if your dependency tree includes @budibase/backend-core (npm) < 3.33.4, fixed in 3.33.4 . Check your lockfile, including transitive dependencies.

## What it is

Budibase is an open-source low-code platform. Prior to version 3.33.4, a server-side request forgery (SSRF) vulnerability exists in Budibase's REST datasource connector. The platform's SSRF protection mechanism (IP blacklist) is rendered completely ineffective because the BLACKLISTIPS environment variable is not set by default in any of the official deployment configurations. When this variable is empty, the blacklist function unconditionally returns false, allowing all requests through without restriction. This issue has been patched in version 3.33.4.

## Affected packages

- npm `@budibase/backend-core` < 3.33.4 → fixed: 3.33.4

## Affected products (CVE record)

- Budibase budibase: < 3.33.4

## Severity

- GitHub_M CVSS 3.1: 9.6 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N`
- GitHub CVSS 3.1: 9.6 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.43% probability of exploitation activity in the next 30 days; percentile 37.

## Sources

- [GitHub Advisory GHSA-7r9j-r86q-7g45](https://github.com/advisories/GHSA-7r9j-r86q-7g45)
- [CVE.org record CVE-2026-31818](https://www.cve.org/CVERecord?id=CVE-2026-31818)
- [NVD entry CVE-2026-31818](https://nvd.nist.gov/vuln/detail/CVE-2026-31818)
- [github.com](https://github.com/Budibase/budibase/security/advisories/GHSA-7r9j-r86q-7g45)
- [github.com](https://github.com/Budibase/budibase/pull/18236)
- [github.com](https://github.com/Budibase/budibase/commit/5b0fe83d4ece52696b62589cba89ef50cc009732)
- [github.com](https://github.com/Budibase/budibase/releases/tag/3.33.4)

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Source page: https://erroneo.us/security/cve/CVE-2026-31818/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt