Azure Front Door vs. CVE-2025-8671 “MadeYouReset”: Nope, Not Today

What’s going on?

Ah, HTTP/2 — the gift that keeps on giving. On August 13, 2025, a shiny new DoS vulnerability popped up: CVE-2025-8671, lovingly nicknamed MadeYouReset. The trick? Attackers spam servers with stream resets inside a single connection. Translation: your backend spends its time canceling stuff instead of doing actual work. Congratulations, you just got DoS’ed for free.

Why should we care?

Because in the wrong hands, this isn’t just “oops, a glitch.” It’s like someone ringing your doorbell a thousand times, then running away — only instead of you ignoring them, your system throws a tantrum and eats its own CPU.

And yes, a whole list of projects got dragged into this mess: Apache, Netty, Fastly, Envoy, NGINX… basically anyone who thought HTTP/2 was cool.

Where’s Microsoft in all this?

Here’s the twist: if you’re using Azure Front Door, you’re already protected. No patches, no downtime, no sweat. Why? Because back in 2023, when CVE-2023-44487 (Rapid Reset) came knocking, Microsoft engineers decided to fix the entire reset logic — not just the one-off bug.

So instead of “let’s just block client-initiated resets,” they went full chef’s kiss and rewired how cancellations work altogether. Any reset — no matter the reason — gets safely handled. Which means MadeYouReset is basically dead on arrival in Azure Front Door.

So what do I have to do?

  • Nothing. Yep. Your Front Door already shrugs this off.

  • Maybe sip your coffee slower. That’s it.

  • Unless… you’re also running self-hosted HTTP/2 servers (NGINX, Apache, etc.). In that case: patch, firewall, rate limits. Don’t procrastinate.

My inner skeptic (because you know I can’t resist):

  • Front Door ≠ the whole world. Just because Azure is safe doesn’t mean your random Kubernetes ingress controller is. Double-check your stack.

  • Exploit status: No public PoC yet, but you know how this goes. Give it a week, and some kid on GitHub will publish a “MadeYouReset.py” for fun.

  • Lesson learned: Security through “we already fixed this two years ago” is great, but the rest of the ecosystem? Still on fire.

TL;DR

  • Vuln: CVE-2025-8671 (MadeYouReset) — HTTP/2 reset abuse = DoS.

  • Impact: Many HTTP/2 implementations.

  • Azure Front Door: Already immune since 2023 (Rapid Reset patch FTW).

  • Action: If you’re on Front Door — chill. If you’re not — start patching, buddy.