I did not try to exploit anything. I measured one thing: does the client hand a Brotli response to Node's Brotli decoder? The bug lives in that decoder, so a client that never feeds it attacker-controlled bytes cannot hit the bug through that path. Upgrading Node to 22.23.4 / 24.22.1 / 26.12.1 is still the real fix.
- A local server always answers
Content-Encoding: br, with a tiny valid Brotli body. No malformed data. - The client asks only for
gzip, deflate. A hostile server ignores what you ask for.