# CVE-2026-12856: Vscode-java: vscode: command injection vulnerability in the javadoc hover provider of the vscode-java extension

> Attackers can execute arbitrary VS Code commands via malicious JavaDoc links, potentially leading to full system compromise in trusted workspaces.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 29 Jun 2026
- **Updated:** 15 Jul 2026
- **Also known as:** GHSA-7vqr-7r5j-c84j

## What is CVE-2026-12856?

CVE-2026-12856 is a high-severity command injection vulnerability in Red Hat OpenShift Dev Spaces 3.29, published on 29 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

A flaw was found in the vscode-java extension, which provides Java language support for Visual Studio Code. The extension incorrectly trusts all Markdown content in JavaDoc hovers, allowing a malicious Java file to include hidden commands. If a user clicks a specially crafted link within a JavaDoc hover popup, an attacker can execute arbitrary VS Code commands, which can lead to full system compromise in trusted workspaces.

Weakness: CWE-88 (Improper Neutralization of Argument Delimiters in a Command)

## Which versions are affected by CVE-2026-12856?

It affects 1 product.


Products: Redhat Openshift Dev Spaces.

## How do I fix CVE-2026-12856?

No fix has been published for CVE-2026-12856 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-12856 being exploited?

There is no known exploitation of CVE-2026-12856 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-12856 and fix it if it is affected.

What it is: CVE-2026-12856 is a high-severity command injection vulnerability in Red Hat OpenShift Dev Spaces 3.29, published on 29 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-12856 in the wild and no public exploit code.

Affected product: Red Hat OpenShift Dev Spaces 3.29. 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-2026-12856/ (Markdown: https://insights.sbomify.com/CVE-2026-12856/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-12856
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-12856
- OSV: https://osv.dev/vulnerability/CVE-2026-12856

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-12856/
Summaries are generated and may contain mistakes; the official description above is the record.