# CVE-2026-103659: MISP: Object Distribution ACL Bypass via Event Flattening Exposes Organisation-Only Attributes

> Authenticated users can bypass access controls to view restricted threat intelligence attributes via event flattening, exposing sensitive organizational data.

- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/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:** 1 Oct 2026
- **Updated:** 1 Oct 2026
- **Also known as:** GHSA-r4v7-fgm4-552c

## What is CVE-2026-103659?

CVE-2026-103659 is a high-severity missing authorization vulnerability in MISP, published on 1 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

MISP contains an authorization bypass in the event flattening feature. When a user requests an event with the flatten option enabled, the application removes the Object containment from the query and returns object attributes as top-level event attributes. In doing so, the object-level distribution and sharing-group access control check was not re-applied to those attributes.

As a result, a user who can view a community-distributed event could retrieve attributes belonging to organisation-only objects (distribution level 0) or objects restricted to a specific sharing group, even though the user's organisation does not have access to those objects. This constitutes an unauthorized disclosure of sensitive threat intelligence data.

A secondary issue was introduced by the initial remediation: the fix reused the full Object contain conditions (including soft-delete state) as the gate for flattened attributes, causing an event owner requesting deleted attributes to lose all attributes whose parent object was still live. The final fix isolates the distribution ACL condition as the sole gate.

Preconditions:

- An authenticated user with access to a community-distributed event

- The event contains at least one object with a distribution level or sharing group that restricts access beyond the event's own distribution

Impact:

- Unauthorized disclosure of attributes belonging to restricted objects

- Potential exposure of organisation-specific threat intelligence to other organisations

Affected versions: <2.5.48

Weakness: CWE-862 (Missing Authorization), CWE-285 (Improper Authorization)

## Which versions are affected by CVE-2026-103659?


## How do I fix CVE-2026-103659?

No fix has been published for CVE-2026-103659 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-103659 being exploited?

There is no known exploitation of CVE-2026-103659 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-103659 and fix it if it is affected.

What it is: CVE-2026-103659 is a high-severity missing authorization vulnerability in MISP, published on 1 Oct 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-2026-103659 in the wild and no public exploit code.

Affected product: 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-2026-103659/ (Markdown: https://insights.sbomify.com/CVE-2026-103659/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-103659
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-103659
- OSV: https://osv.dev/vulnerability/CVE-2026-103659

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-103659/
Summaries are generated and may contain mistakes; the official description above is the record.