Node.js, despite being based on V8, is still susceptible independently of V8 and introduces its own vulnerabilities. It's not sufficient for the runtime to be secure, but the new facilities Bun provides must also be vetted.
Bun/Oven are new, and similar in position to Node. Here are the hard questions I'd ask if I were on a security team and asked to review adopting Bun:
1. Will Oven adopt a security policy for Bun? (https://github.com/oven-sh/bun/security)
2. What measures is Oven taking to proactively detect and mitigate vulnerabilities? (e.g.: fuzzing, audits, bug bounties)
3. Will Oven support Zig development to avoid an existential risk in upstream vulnerabilities?