CVE-2026-47092: Claude HUD Command Injection Vulnerability

CVE-2026-47092 Overview

CVE-2026-47092 is a command injection vulnerability in Claude HUD versions through 0.0.12 on Windows systems. The flaw allows local attackers to execute arbitrary commands by manipulating the COMSPEC environment variable before claude-hud performs its version check. When the application calls execFile() with cmd.exe arguments, it trusts the attacker-controlled COMSPEC value, causing the attacker-supplied executable to run with the user's privileges. The issue is tracked under CWE-427: Uncontrolled Search Path Element and was patched in commit 234d9aa.

Critical Impact
Local attackers on Windows can achieve arbitrary code execution by setting COMSPEC to a malicious binary before claude-hud invokes its Windows version lookup routine.

Affected Products

Claude HUD through version 0.0.12
Windows installations of claude-hud relying on the COMSPEC environment variable
Deployments prior to patch commit 234d9aa

Discovery Timeline

2026-05-18 - CVE-2026-47092 published to NVD
2026-05-18 - Last updated in NVD database
Patch reference - Fixed in commit 234d9aad919b51326a43bcf90b45ae35c23afc30 via pull request #487

Technical Details for CVE-2026-47092

Vulnerability Analysis

Claude HUD performs a Windows version lookup by invoking cmd.exe through Node.js execFile(). The implementation resolves the command interpreter path from the COMSPEC environment variable without validation. An attacker with local access can override COMSPEC to point to any executable on disk. When claude-hud runs its version check, execFile() launches the attacker-controlled binary instead of the legitimate Windows command processor.

The vulnerability is categorized as CWE-427: Uncontrolled Search Path Element. The application implicitly trusts a user-controlled environment variable to locate a critical system binary. This pattern bypasses any sandboxing assumptions tied to launching cmd.exe directly.

Root Cause

The root cause is reliance on the COMSPEC environment variable to locate the Windows command interpreter. Node.js execFile() does not perform shell parsing, but it executes whatever path is supplied as the executable argument. By reading COMSPEC without canonicalization or allowlisting, claude-hud allows substitution of the interpreter with arbitrary binaries.

Attack Vector

Exploitation requires local access and the ability to set environment variables in the user session. An attacker sets COMSPEC to the path of a malicious executable, then triggers claude-hud functionality that invokes the Windows version lookup. The execution context matches the user running claude-hud, enabling code execution within that user's security boundary.

typescript

// Security patch in src/git.ts — harden links and Windows version lookup (#487)
         .replace(/^git@([^:]+):/, 'https://$1/')
         .replace(/\.git$/, '');
       if (httpsBase.startsWith('https://')) {
-        branchUrl = `${httpsBase}/tree/${branch}`;
+        branchUrl = `${httpsBase}/tree/${encodeURIComponent(branch)}`;
       }
     } catch {
       // No remote or not GitHub
// Source: https://github.com/jarrodwatts/claude-hud/commit/234d9aad919b51326a43bcf90b45ae35c23afc30

typescript

// Security patch in src/transcript.ts — adds path canonicalization (#487)
   return path.join(getHudPluginDir(homeDir), 'transcript-cache', `${hash}.json`);
 }

+function canonicalizeTranscriptPath(transcriptPath: string): string | null {
+  try {
+    return fs.realpathSync(transcriptPath);
+  } catch {
+    return null;
+  }
+}
+
 function readTranscriptFileState(transcriptPath: string): TranscriptFileState | null {
   try {
     const stat = fs.statSync(transcriptPath);
// Source: https://github.com/jarrodwatts/claude-hud/commit/234d9aad919b51326a43bcf90b45ae35c23afc30

The patch hardens link generation through encodeURIComponent() and introduces canonicalizeTranscriptPath() using fs.realpathSync() to resolve symbolic links and validate filesystem paths before use. See VulnCheck's advisory for additional technical detail.

Detection Methods for CVE-2026-47092

Indicators of Compromise

Modifications to the COMSPEC environment variable in user or process scope on Windows hosts running claude-hud
execFile() or child process spawns originating from claude-hud where the executable path is not C:\Windows\System32\cmd.exe
Unexpected child processes launched by the Node.js runtime hosting claude-hud during version check operations

Detection Strategies

Monitor process creation events on Windows endpoints for claude-hud child processes that resolve through a non-default COMSPEC value
Audit environment variable changes scoped to user sessions, focusing on COMSPEC and other interpreter-path variables
Correlate claude-hud execution with the presence of suspicious binaries placed in user-writable directories that match a modified COMSPEC

Monitoring Recommendations

Enable Windows Event Log auditing for process creation (Event ID 4688) with command-line capture enabled
Track Node.js process trees originating from claude-hud installations and alert on non-standard executables
Maintain inventory of claude-hud versions across endpoints and flag deployments older than the 234d9aa patch

How to Mitigate CVE-2026-47092

Immediate Actions Required

Upgrade claude-hud to a build that includes commit 234d9aa or later
Restrict local accounts that can run claude-hud to trusted users until patches are applied
Reset and audit the COMSPEC environment variable on affected Windows hosts to ensure it points to %SystemRoot%\System32\cmd.exe

Patch Information

The vendor patched the vulnerability in commit 234d9aad919b51326a43bcf90b45ae35c23afc30, released through pull request #487. The fix hardens the Windows version lookup path and adds canonicalization for transcript file paths. Reference the original issue report #485 for context.

Workarounds

Explicitly set COMSPEC to the absolute path of the legitimate cmd.exe in any session running claude-hud
Apply Windows AppLocker or Windows Defender Application Control policies to block execution of unsigned binaries from user-writable directories
Avoid running claude-hud under privileged accounts on shared or multi-user Windows hosts

bash

# Verify and pin COMSPEC to the legitimate Windows command interpreter
setx COMSPEC "%SystemRoot%\System32\cmd.exe"

# Confirm installed claude-hud version is patched
npm ls claude-hud