# CVE-2026-88915: MISP Event Template Instantiation Bypasses Sharing Group and Tagging Authorization

> Attackers can bypass sharing group and tagging authorization checks when instantiating MISP event templates, potentially exposing restricted data.

- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/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:** 10 Sep 2026
- **Updated:** 10 Sep 2026
- **Also known as:** GHSA-46cw-r5cx-57f2

## What is CVE-2026-88915?

CVE-2026-88915 is a high-severity missing authorization vulnerability in MISP, published on 10 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Affected versions of MISP do not consistently enforce the acting user's authorization when instantiating event templates.

For templates using distribution = 4, the template can specify a sharing_group_id. The instantiation path passed that value into event creation without verifying that the user instantiating the template was actually permitted to use the selected sharing group. The commit notes that Event::_add() only performed its own sharing-group authorization in another code path, leaving template instantiation able to write the identifier directly.

The same instantiation path also attached template-specified tags without checking the user's normal tagging permissions. In addition, it hardcoded local => 0, meaning tags marked local_only could be attached globally and consequently propagate through synchronization or export, contrary to their intended restriction.

The fix adds explicit SharingGroup::canUse() authorization for the acting user, applies the same tag-modification checks used by normal event tagging, and ensures local_only tags are attached locally.

Version affected: ≤2.5.45

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-88915?


## How do I fix CVE-2026-88915?

No fix has been published for CVE-2026-88915 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-88915 being exploited?

There is no known exploitation of CVE-2026-88915 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-88915 and fix it if it is affected.

What it is: CVE-2026-88915 is a high-severity missing authorization vulnerability in MISP, published on 10 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-2026-88915 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-2026-88915/ (Markdown: https://insights.sbomify.com/CVE-2026-88915/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-88915
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-88915
- OSV: https://osv.dev/vulnerability/CVE-2026-88915

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-88915/
Summaries are generated and may contain mistakes; the official description above is the record.