# CVE-2026-9136: Unauthorized ShadowAttribute modification in MISP via client-supplied identifier

> Authenticated users can modify unauthorized shadow attributes by supplying existing IDs, allowing data tampering and potential information disclosure.

- **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:** 20 May 2026
- **Updated:** 20 May 2026
- **Also known as:** GHSA-hfjr-4239-84fm

## What is CVE-2026-9136?

CVE-2026-9136 is a high-severity missing authorization vulnerability in Misp-Project Misp, published on 20 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability was identified in the ShadowAttribute proposal creation workflow. The add action accepted user-controlled ShadowAttribute request data without removing the id field before saving the record. Because the underlying framework treats a supplied primary key as an instruction to update an existing record, an authenticated user able to submit shadow attribute proposals could provide the identifier of an existing ShadowAttribute and cause that record to be updated instead of creating a new proposal.

This can result in unauthorized modification of existing shadow attributes, potentially affecting proposals associated with events the user should not be able to alter. Depending on deployment configuration and accessible API responses, the issue may also expose or move proposal data across event contexts.

The vulnerability is caused by trusting a client-supplied primary key during object creation. The fix removes the id field from incoming ShadowAttribute data before processing, ensuring that the endpoint always creates a new proposal rather than updating an existing one. This has been fixed in MISP 2.5.38.

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

## Which versions are affected by CVE-2026-9136?

It affects 1 product.


Products: Misp-Project Misp.

## How do I fix CVE-2026-9136?

No fix has been published for CVE-2026-9136 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-9136 being exploited?

There is no known exploitation of CVE-2026-9136 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-2026-9136 and fix it if it is affected.

What it is: CVE-2026-9136 is a high-severity missing authorization vulnerability in Misp-Project Misp, published on 20 May 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-2026-9136 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-2026-9136/ (Markdown: https://insights.sbomify.com/CVE-2026-9136/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-9136
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-9136
- OSV: https://osv.dev/vulnerability/CVE-2026-9136

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-9136/
Summaries are generated and may contain mistakes; the official description above is the record.