# CVE-2026-72859: Budibase 3.39.4 before 3.40.0 Authorization Regression via S3 Presigned URL

> BASIC users can generate S3 presigned URLs to upload files to arbitrary buckets due to a permission check regression in the attachment endpoint.

- **Severity:** High 8.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Aug 2026
- **Updated:** 8 Oct 2026
- **Also known as:** GHSA-9pwj-99rm-cq6j, GHSA-xcx6-4f2g-hhgx

## What is CVE-2026-72859?

CVE-2026-72859 is a high-severity missing authorization vulnerability in budibase server, published on 14 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Budibase versions 3.39.4 before 3.40.0 contain an authorization regression in the S3 attachment upload endpoint that allows BASIC users to obtain S3 PutObject presigned URLs by sending POST requests to the attachments endpoint. The route was changed from a BUILDER permission check to a TABLE/WRITE check, which BASIC users hold by default. Attackers can specify arbitrary S3 buckets in the request body to generate presigned URLs for writing to any bucket accessible by the stored IAM credentials, enabling unauthorized file uploads.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-72859?

2 open source packages ship an affected version, including @budibase/server.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@budibase/server` | npm | All versions to 3.38.1 | None |
| `@budibase/server` | npm | All versions to 3.38.1 | None |

## How do I fix CVE-2026-72859?

No fix has been published for CVE-2026-72859 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-72859 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-72859 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72859 and fix it if it is affected.

What it is: CVE-2026-72859 is a high-severity missing authorization vulnerability in budibase server, published on 14 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-72859 exists.

Affected packages and fixed versions:
- @budibase/server (npm): affected all versions up to 3.38.1; no fix listed
- @budibase/server (npm): affected all versions up to 3.38.1; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-72859/ (Markdown: https://insights.sbomify.com/CVE-2026-72859/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72859
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72859
- OSV: https://osv.dev/vulnerability/CVE-2026-72859

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72859/
Summaries are generated and may contain mistakes; the official description above is the record.