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

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-29 · updated 2026-10-25
Weakness: CWE-88

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.

Affected products

Red Hat OpenShift Dev Spaces 3.29: all versions

References

https://access.redhat.com/errata/RHSA-2026:36820
https://access.redhat.com/security/cve/CVE-2026-12856
https://bugzilla.redhat.com/show_bug.cgi?id=2491278
https://github.com/redhat-developer/vscode-java/security/advisories/GHSA-7qv8-6qrw-3crv
https://access.redhat.com/errata/RHSA-2026:36820
https://access.redhat.com/security/cve/CVE-2026-12856
https://bugzilla.redhat.com/show_bug.cgi?id=2491278
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-12856.json

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