# CVE-2026-40937: RustFS: Missing admin authorization on notification target endpoints allows unauthenticated configuration of event webhooks

> Unauthenticated users can configure event webhooks due to missing admin authorization, enabling cross-user event interception and audit evasion.

- **Severity:** High 8.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L`)
- **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:** 22 Apr 2026
- **Updated:** 23 Apr 2026
- **Also known as:** GHSA-pfcq-4gjr-6gjm

## What is CVE-2026-40937?

CVE-2026-40937 is a high-severity missing authorization vulnerability in rustfs, published on 22 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

RustFS is a distributed object storage system built in Rust. Prior to 1.0.0-alpha.94, all four notification target admin API endpoints in `rustfs/src/admin/handlers/event.rs` use a `check_permissions` helper that validates authentication only (access key + session token), without performing any admin-action authorization via `validate_admin_request`. Every other admin handler in the codebase correctly calls `validate_admin_request` with a specific `AdminAction`. This is the only admin handler file that skips authorization. A non-admin user can overwrite a shared admin-defined notification target by name, causing subsequent bucket events to be delivered to an attacker-controlled endpoint. This enables cross-user event interception and audit evasion. 1.0.0-alpha.94 contains a patch.

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-40937?

2 open source packages ship an affected version, including rustfs. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `rustfs` | crates.io | All versions to 0.0.2 | None |
| `rustfs` | crates.io | All versions to 0.0.2 | None |

Products: Rustfs Rustfs.

## How do I fix CVE-2026-40937?

No fix has been published for CVE-2026-40937 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-40937 being exploited?

There is no known exploitation of CVE-2026-40937 in the wild and no public exploit code.

## Other vulnerabilities in rustfs

- [CVE-2025-68926](https://insights.sbomify.com/CVE-2025-68926/): RustFS has a gRPC Hardcoded Token Authentication Bypass (critical 9.8)
- [CVE-2026-27822](https://insights.sbomify.com/CVE-2026-27822/): Rust has Critical Stored XSS in Preview Modal, leading to Administrative Account Takeover (critical 9.1)
- [CVE-2025-68705](https://insights.sbomify.com/CVE-2025-68705/): RustFS Path Traversal Vulnerability (high 8.8)
- [CVE-2026-27607](https://insights.sbomify.com/CVE-2026-27607/): RustFS's Missing Post Policy Validation leads to Arbitrary Object Write (high 8.1)
- [CVE-2026-21862](https://insights.sbomify.com/CVE-2026-21862/): RustFS sourceIp bypass via spoofed X-Forwarded-For/Real-IP headers (high 7.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40937 and fix it if it is affected.

What it is: CVE-2026-40937 is a high-severity missing authorization vulnerability in rustfs, published on 22 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-40937 in the wild and no public exploit code.

Affected packages and fixed versions:
- rustfs (crates.io): affected all versions up to 0.0.2; no fix listed
- rustfs (crates.io): affected all versions up to 0.0.2; 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-2026-40937/ (Markdown: https://insights.sbomify.com/CVE-2026-40937/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40937
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40937
- OSV: https://osv.dev/vulnerability/CVE-2026-40937

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40937/
Summaries are generated and may contain mistakes; the official description above is the record.