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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.

PUBLISHED Reserved 2026-06-22 | Published 2026-06-29 | Updated 2026-07-09 | Assigner redhat




HIGH: 8.8CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Problem types

Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')

Product status

Default status
affected

1782989367 (rpm) before *
unaffected

Timeline

2026-06-20:Reported to Red Hat.
2026-06-29:Made public.

Credits

Red Hat would like to thank byte256 for reporting this issue.

References

access.redhat.com/security/cve/CVE-2026-12856 vdb-entry

bugzilla.redhat.com/show_bug.cgi?id=2491278 (RHBZ#2491278) issue-tracking

security.access.redhat.com/...2/vex/2026/cve-2026-12856.json

access.redhat.com/errata/RHSA-2026:36820 vendor-advisory

access.redhat.com/errata/RHSA-2026:36820 (RHSA-2026:36820) vendor-advisory

access.redhat.com/security/cve/CVE-2026-12856 vdb-entry

bugzilla.redhat.com/show_bug.cgi?id=2491278 (RHBZ#2491278) issue-tracking

github.com/...e-java/security/advisories/GHSA-7qv8-6qrw-3crv

cve.org (CVE-2026-12856)

nvd.nist.gov (CVE-2026-12856)

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