# CVE-2026-76404: Remote Code Execution (RCE) through Deserialization of Untrusted Data in Splunk MCP Server app

> An admin user can execute arbitrary OS commands via unsafe deserialization in the credential management component of the Splunk MCP Server app.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 19 Aug 2026
- **Updated:** 20 Aug 2026
- **Also known as:** GHSA-3v49-2fcm-3rcj

## What is CVE-2026-76404?

CVE-2026-76404 is a critical unsafe deserialization vulnerability in Splunk MCP Server app, published on 19 Aug 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

In Splunk MCP Server app versions below 1.2.1, a user who holds the "admin" Splunk role could execute arbitrary commands on the underlying operating system. The vulnerability is possible because of missing input validation in the app's credential management component, which deserializes stored data without checking whether the content is of the expected type.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2026-76404?

It affects 1 product.


Products: Splunk Model Context Protocol Server.

## How do I fix CVE-2026-76404?

No fix has been published for CVE-2026-76404 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-76404 being exploited?

There is no known exploitation of CVE-2026-76404 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-76404 and fix it if it is affected.

What it is: CVE-2026-76404 is a critical unsafe deserialization vulnerability in Splunk MCP Server app, published on 19 Aug 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-76404 in the wild and no public exploit code.

Affected product: Splunk MCP Server app. 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-2026-76404/ (Markdown: https://insights.sbomify.com/CVE-2026-76404/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-76404
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-76404
- OSV: https://osv.dev/vulnerability/CVE-2026-76404

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-76404/
Summaries are generated and may contain mistakes; the official description above is the record.