CVE-2026-12856

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.

CVSS v3.1 Score

8.8

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0030

Probability of exploitation

0.21%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-88 CWE-88

References

Other References

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/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

Frequently Asked Questions

What is CVE-2026-12856? +

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. It has a CVSS v3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-12856? +

CVE-2026-12856 has a CVSS v3.1 score of 8.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0030, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-12856? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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