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CVE Record

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

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.

HighCVSS 8.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This vulnerability lets a malicious Java file hide dangerous VS Code command links inside JavaDoc hover text. A developer must click the crafted hover link, but in a trusted workspace that action can lead to full system compromise.

Executive priority

Treat as high priority for developer environments because compromise can start from source code review behavior. Prioritize teams using OpenShift Dev Spaces or vscode-java with trusted workspaces, especially where developers access secrets, production systems, or build pipelines.

Technical view

The vscode-java JavaDoc hover provider incorrectly trusts Markdown content. Malicious JavaDoc can embed a crafted link that executes arbitrary VS Code commands after user interaction. Red Hat rates this high, CVSS 8.8, CWE-88, affecting OpenShift Dev Spaces 3.29 pluginregistry-rhel9 version 1782989367.

Likely exposure

The source bundle specifically lists Red Hat OpenShift Dev Spaces 3.29, devspaces/pluginregistry-rhel9 version 1782989367, as affected. It also describes the underlying flaw in the Red Hat vscode-java extension. It does not establish broader product or version impact.

Exploitation context

No source in the bundle reports active exploitation, and KEV is false. Exploitation requires user interaction: clicking a specially crafted JavaDoc hover link in a trusted workspace containing a malicious Java file.

Researcher notes

The core issue is command injection through trusted Markdown rendering in JavaDoc hover content. Evidence supports user-assisted exploitation with severe impact, but does not include exploit-in-the-wild claims or complete version range details beyond the Red Hat affected package entry.

Mitigation direction

  • Apply Red Hat guidance from RHSA-2026:36820 when available for your environment.
  • Review the GitHub advisory for vscode-java remediation details.
  • Avoid opening untrusted Java projects in trusted workspaces until remediated.
  • Warn developers not to click unexpected links in JavaDoc hover popups.
  • Inventory OpenShift Dev Spaces pluginregistry-rhel9 deployments for affected versions.

Validation and detection

  • Check OpenShift Dev Spaces version and pluginregistry-rhel9 package version.
  • Confirm whether vscode-java is installed in developer workspaces.
  • Review workspace trust settings for Java development environments.
  • Verify remediation status against Red Hat CVE and errata pages.
  • Monitor Red Hat Bugzilla and GHSA for updated affected-version details.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · medium confidence lookup

CWE-88: Command execution behavior lookup

Command injection weaknesses can lead defenders to review execution techniques and command interpreter telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
description · low confidence lookup

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-12856 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.8 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
7Timeline events
2ADP providers
6Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: total

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
8.8CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H2.85.9redhat
8.8CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H2.85.9redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

8.8High
CVSS 3.1 vector shape for CVE-2026-12856Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. ADP timelineredhat-SADP

    Reported to Red Hat.

  2. Source timelineredhat

    Reported to Red Hat.

  3. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  4. ADP timelineredhat-SADP

    Made public.

  5. Source timelineredhat

    Made public.

  6. CVE publishedCVE Program

    The CVE record was published.

  7. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPvscode-java: vscode: Command Injection vulnerability in the JavaDoc hover provider of the vscode-java extension
other:Red Hat severity ratingcvssV3_1
  • 2026-06-20T17:33:27.000Z: Reported to Red Hat.
  • 2026-06-29T12:25:07.165Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Red HatRed Hat OpenShift Dev Spaces 3.29devspaces/pluginregistry-rhel9, 1782989367affected
Weakness

CWE details

CWE-88

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-88 · source CWE mapping

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

Improper Neutralization of Argument Delimiters in a Command ('Argument Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs