Cloudflare tests Anthropic's code-finding AI on real repositories
Original: CloudFlare's post is one of the better written reports on Mythos.
Source: x.com ↗
Who: Posted by @merill (Microsoft identity and Entra platform engineer, known for tracking enterprise AI tooling), sharing a security research post by Cloudflare's internal security team.
What's new: Cloudflare's security team ran a controlled test of , Anthropic's offensive-security AI model, against fifty of Cloudflare's own production repositories. The headline finding is that Mythos can meaningfully identify real vulnerabilities in real, production-grade code — not toy examples — and that this changes what defenders have to plan for.
How it works: Mythos was given access to Cloudflare's actual source repositories and tasked with finding exploitable weaknesses, much like a hired would be. Cloudflare's team then reviewed what the model surfaced and compared it against what their own engineers and traditional automated scanners had previously flagged. The post argues the right response is not simply to patch faster, but to rethink the structural architecture around how vulnerabilities are discovered, prioritized, and contained — essentially treating AI-assisted attack as a permanent background condition rather than a one-off threat to outrun.
Why it matters: When an AI can do credible offensive security work against fifty real codebases in weeks, the old mental model of "find the bug, ship the fix" breaks down. The bottleneck is no longer spotting vulnerabilities — it is having the organizational and architectural layers in place so that any single unfixed bug cannot become a catastrophic breach. Cloudflare is signaling to the industry that and reactive patching pipelines are insufficient against adversaries who can now rent this kind of capability.
Caveats: The source is a single social-media endorsement with no quoted figures, no pass rates, and no independent replication. The full Cloudflare post sits behind the linked URL, and the summary above is reconstructed from what Cloudflare describes in that post. Readers wanting concrete numbers — how many bugs found, how many were novel, false-positive rate — should read the primary source directly.