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In 2024 and 2025, we reassessed remote Spectre attacks on our Workers infrastructure. We share details about the new attack primitives like Spectre gadgets, remote timers, achieving co-location and how new defenses further harden Cloudflare Workers.
Cloudflare has deployed two WAF rules in response to high-severity vulnerabilities disclosed to us by the WordPress security team. The new rules protect all Cloudflare customers using affected WordPress versions, but customers should still update immediately to a patched release
We break down the technical architecture behind our multi-stage vulnerability discovery harness and automated triage loop. Learn how we manage state controls, squash false positives through adversarial review, and route around LLM context limits.
When a critical Linux kernel privilege escalation was publicly disclosed, Cloudflare's security and engineering teams detected, investigated, and mitigated the threat across our global fleet, confirming zero customer impact and no malicious exploitation.
Cloudflare’s new Web and API Vulnerability Scanner helps teams proactively find logic flaws. By using AI to build API call graphs, we identify vulnerabilities that standard defensive tools miss.
Cloudflare is introducing Attack Signature Detection and Full-Transaction Detection to provide continuous, high-fidelity security insights without the manual tuning of traditional WAFs. By correlating request payloads with server responses, we can now identify successful exploits and data exfiltration while minimizing false positives.
A vulnerability was recently identified in Cloudflare’s automation of certificate validation. Here we explain the vulnerability and outline the steps we’ve taken to mitigate it.
Early activity indicates that threat actors quickly integrated this vulnerability into their scanning and reconnaissance routines and targeted critical infrastructure including nuclear fuel, uranium and rare earth elements. We outline the tactics they appear to be using and how Cloudflare is protecting customers.
Cloudflare offers protection against a new high profile vulnerability for React Server Components: CVE-2025-55182. All WAF customers are automatically protected as long as the WAF is deployed.
We identified and patched two DDoS vulnerabilities in our QUIC implementation related to packet acknowledgements. Cloudflare customers were not affected. We examine the "Optimistic ACK" attack vector and our solution, which dynamically skips packet numbers to validate client behavior.
We are further hardening Cloudflare Workers with the latest software and hardware features. We use defense-in-depth, including V8 sandboxes and the CPU's memory protection keys to keep your data safe.
A new HTTP/2 denial-of-service (DoS) vulnerability called MadeYouReset was recently disclosed by security researchers. Cloudflare HTTP DDoS mitigation, already protects from MadeYouReset.
An upcoming vulnerability disclosure in Cloudflare’s SSL for SaaSv1 is detailed, explaining the steps we’ve taken towards deprecation.
Cloudflare patched a Mutual TLS (mTLS) vulnerability (CVE-2025-23419) reported via its Bug Bounty Program. The flaw in session resumption allowed client certificates to authenticate across different
The RADIUS protocol is commonly used to control administrative access to networking gear. Despite its importance, RADIUS hasn’t changed much in decades. We discuss an attack on RADIUS as a case study for why it’s important for legacy protocols to keep up with advancements in cryptography
polyfill.io, a popular JavaScript library service, can no longer be trusted and should be removed from websites
In April and May 2024, Cloudforce One employed proactive defense measures to successfully prevent Russia-aligned threat actor FlyingYeti from launching their latest phishing campaign targeting Ukraine
The Workers AI and AI Gateway team recently collaborated closely with security researchers at Ben Gurion University regarding a report submitted through our Public Bug Bounty program. Through this process, we discovered and fully patched a vulnerability affecting all LLM providers. Here’s the story
