# CVE-2026-103239: MISP Tag Collection Save Allows Privilege Escalation via Sibling Model Injection

> Authenticated tag editors can escalate privileges to site administrator by injecting sibling model data into tag collection save requests.

- **Severity:** High 8.6 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/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:** 30 Sep 2026
- **Updated:** 30 Sep 2026
- **Also known as:** GHSA-vpmp-h7jx-6gfx

## What is CVE-2026-103239?

CVE-2026-103239 is a high-severity vulnerability in MISP, published on 30 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

MISP contains a privilege escalation vulnerability in the tag collection creation and editing functionality. The affected actions accepted the full HTTP request payload and passed it to a bulk-association save operation, which writes not only the intended tag collection record but also any associated model data present in the payload.

A user holding the tag editor permission could craft a request that includes additional model data (such as User or Organisation records) alongside the tag collection fields. Because the save operation processed all associated models indiscriminately, the injected sibling records were written to the database, enabling the attacker to modify or create privileged accounts and escalate to site administrator.

Preconditions:

- An authenticated account with the tag editor permission (perm_tag_editor)

- Network access to the MISP instance

Impact:

- Unauthorized creation or modification of User and Organisation records

- Privilege escalation from tag editor to site administrator

Affected versions: < 2.5.48

Weakness: CWE-862 (Missing Authorization), CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2026-103239?


## How do I fix CVE-2026-103239?

No fix has been published for CVE-2026-103239 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-103239 being exploited?

There is no known exploitation of CVE-2026-103239 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-103239 and fix it if it is affected.

What it is: CVE-2026-103239 is a high-severity vulnerability in MISP, published on 30 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-2026-103239 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-2026-103239/ (Markdown: https://insights.sbomify.com/CVE-2026-103239/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-103239
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-103239
- OSV: https://osv.dev/vulnerability/CVE-2026-103239

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-103239/
Summaries are generated and may contain mistakes; the official description above is the record.