# CVE-2026-104907: MISP: JavaScript Injection via Remote Tag ID in Event Preview Inline Handler

> Attackers can execute arbitrary JavaScript in MISP users' browsers via malicious tag IDs from linked servers, requiring remote server configuration.

- **Severity:** Medium 4.8 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 2 Oct 2026
- **Updated:** 2 Oct 2026
- **Also known as:** GHSA-4g8m-xfv2-jhr3

## What is CVE-2026-104907?

CVE-2026-104907 is a medium-severity cross-site scripting vulnerability in MISP, published on 2 Oct 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

MISP contains a cross-site scripting (XSS) vulnerability in the remote event preview page. When a linked (remote) MISP server is configured, the event preview renders tag identifiers inside an inline JavaScript onclick attribute. The tag ID value was HTML-escaped but not sanitized for the JavaScript string context, meaning a malicious linked server could supply a tag ID containing characters (such as a single quote) that break out of the JavaScript string literal and inject arbitrary script.

Preconditions:

- A linked/remote MISP server is configured and connected to the local instance.

- The linked server supplies a crafted tag ID in an event.

- An authenticated user views the event preview and interacts with the affected tag element.

Impact:

- Arbitrary JavaScript execution in the context of the viewing user's browser session, potentially allowing session hijacking, data exfiltration, or unauthorized actions on behalf of the user.

Affected versions: MISP prior to the fix commit (v2.5.48 or later, exact boundary unconfirmed).

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation), CWE-116 (Improper Encoding or Escaping of Output)

## Which versions are affected by CVE-2026-104907?


## How do I fix CVE-2026-104907?

No fix has been published for CVE-2026-104907 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-104907 being exploited?

There is no known exploitation of CVE-2026-104907 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-104907 and fix it if it is affected.

What it is: CVE-2026-104907 is a medium-severity cross-site scripting vulnerability in MISP, published on 2 Oct 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-104907 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-2026-104907/ (Markdown: https://insights.sbomify.com/CVE-2026-104907/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-104907
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104907
- OSV: https://osv.dev/vulnerability/CVE-2026-104907

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-104907/
Summaries are generated and may contain mistakes; the official description above is the record.