# CVE-2026-86451: MISP Event Graph Object Reference Lookup Exposes References from Unauthorized Objects

> Authenticated users can retrieve unauthorized object reference data by UUID due to missing access control checks in MISP.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/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:** 7 Sep 2026
- **Updated:** 8 Sep 2026
- **Also known as:** GHSA-hf4f-66qc-r3jh

## What is CVE-2026-86451?

CVE-2026-86451 is a medium-severity missing authorization vulnerability in Misp-Project Misp, published on 7 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Affected versions of MISP allow authenticated users to retrieve object-reference records by UUID through EventGraphTool::get_reference_data() without first checking whether the requester is authorized to view the object the reference belongs to.

The vulnerable code queried ObjectReference.uuid directly and returned the matching row whenever it existed. Because no parent-object ACL was applied, a user who knew or obtained a reference UUID could retrieve information associated with an object outside their normal access scope. The commit explicitly states that any object reference could be returned by UUID without authorizing its parent object.

The fix retrieves the referenced object's object_id and calls fetchObjectSimple() with the current user. If the user cannot access that parent object, MISP now returns NotFoundException instead of exposing the reference.

Version affected: ≤2.5.45

Weakness: CWE-862 (Missing Authorization), CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-86451?

It affects 1 product.


Products: Misp-Project Misp.

## How do I fix CVE-2026-86451?

No fix has been published for CVE-2026-86451 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-86451 being exploited?

There is no known exploitation of CVE-2026-86451 in the wild and no public exploit code.

## Other vulnerabilities in Misp-Project Misp

- [CVE-2024-46918](https://insights.sbomify.com/CVE-2024-46918/): Missing authorization in n/a (critical 9.8)
- [CVE-2024-45509](https://insights.sbomify.com/CVE-2024-45509/): Missing authorization in n/a (critical 9.8)
- [CVE-2024-29858](https://insights.sbomify.com/CVE-2024-29858/): File upload in n/a (critical 9.8)
- [CVE-2024-29859](https://insights.sbomify.com/CVE-2024-29859/): File upload in n/a (critical 9.8)
- [CVE-2024-25674](https://insights.sbomify.com/CVE-2024-25674/): File upload in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-86451 and fix it if it is affected.

What it is: CVE-2026-86451 is a medium-severity missing authorization vulnerability in Misp-Project Misp, published on 7 Sep 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-2026-86451 in the wild and no public exploit code.

Affected product: Misp-Project Misp. 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-2026-86451/ (Markdown: https://insights.sbomify.com/CVE-2026-86451/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-86451
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-86451
- OSV: https://osv.dev/vulnerability/CVE-2026-86451

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-86451/
Summaries are generated and may contain mistakes; the official description above is the record.