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

Should you act?

Critical, preconditions apply

Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• 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.

From the GitHub advisory

1. Summary

| Field | Value | |-------|-------| | Title | SSRF via REST Connector with Empty Default Blacklist Leading to Full Internal Data Exfiltration | | Product | Budibase | | Version | 3.30.6 (latest stable as of 2026-02-25) | | Component | REST Datasource Integration + Backend-Core Blacklist Module | | Severity | Critical | | Attack Vector | Network | | Privileges Required | Low (Builder role, or QUERY WRITE for execution of pre-existing queries) | | User Interaction | None | | Affected Deployments | All self-hosted instances without explicit BLACKLISTIPS configuration (believed to be the vast majority) |

---

2. Description

A critical 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.

Weakness type: CWE-918, CWE-1188.

Product: @budibase/backend-core (npm) · Assigned by: GitHub_M · Published: 2026-04-03

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: low (any account)
• User interaction: none
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• 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.

Timeline

• 2026-04-03 — CVE record last updated
• 2026-04-03 — CVE record published by GitHub_M
• 2026-04-03 — GitHub-reviewed advisory GHSA-7r9j-r86q-7g45 published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-7r9j-r86q-7g45 github.com
2. CVE.org record CVE-2026-31818 cve.org
3. NVD entry CVE-2026-31818 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com

Critical npm advisories · Today’s Security Digest