# CVE-2026-85390: Checkmate through 3.11.0 Missing Authorization on Maintenance Window, Notification, and Check Deletion Routes

> Read-only users can perform administrative actions like deleting checks and modifying notifications due to missing authorization guards.

- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/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:** 3 Sep 2026
- **Updated:** 5 Sep 2026
- **Also known as:** GHSA-8cvg-rxfw-4pf6

## What is CVE-2026-85390?

CVE-2026-85390 is a high-severity missing authorization vulnerability in bluewave-labs Checkmate, published on 3 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Checkmate through 3.11.0 omits the isAllowed role guard middleware on maintenance-window, notification, and check-deletion routes, allowing read-only users to perform administrative actions. Attackers with user-role sessions can create arbitrary maintenance windows to silence alerts, modify notification channels, and delete monitor check history to erase incident evidence.

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-85390?


## How do I fix CVE-2026-85390?

No fix has been published for CVE-2026-85390 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-85390 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-85390 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-85390 and fix it if it is affected.

What it is: CVE-2026-85390 is a high-severity missing authorization vulnerability in bluewave-labs Checkmate, published on 3 Sep 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-2026-85390 exists.

Affected product: bluewave-labs Checkmate. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-85390/ (Markdown: https://insights.sbomify.com/CVE-2026-85390/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-85390
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-85390
- OSV: https://osv.dev/vulnerability/CVE-2026-85390

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-85390/
Summaries are generated and may contain mistakes; the official description above is the record.