Tag Archives: waf

Resolving a Mutual TLS session resumption vulnerability

On January 23, 2025, Cloudflare was notified via its Bug Bounty Program of a vulnerability in Cloudflare’s Mutual TLS (mTLS) implementation.  The vulnerability affected customers who were using mTLS and involved a flaw in our session resumption handling. Cloudflare’s investigation revealed no evidence that the vulnerability was being actively exploited. And tracked as CVE-2025-23419, Cloudflare […]

All Cloudflare Customers Protected from Atlassian Confluence CVE-2023-22515

On 2023-10-04 at 13:00 UTC, Atlassian released details of the zero-day vulnerability described as “Privilege Escalation Vulnerability in Confluence Data Center and Server” (CVE-2023-22515), a zero-day vulnerability impacting Confluence Server and Data Center products. Cloudflare was warned about the vulnerability before the advisory was published and worked with Atlassian to proactively apply protective WAF rules […]

Detecting zero-days before zero-day

We are constantly researching ways to improve our products. For the Web Application Firewall (WAF), the goal is simple: keep customer web applications safe by building the best solution available on the market. In this blog post we talk about our approach and ongoing research into detecting novel web attack vectors in our WAF before […]

New! Rate Limiting analytics and throttling

Rate Limiting rules are essential in the toolbox of security professionals as they are very effective in managing targeted volumetric attacks, takeover attempts, scraping bots, or API abuse. Over the years we have received a lot of feature requests from users, but two stand out: suggesting rate limiting thresholds and implementing a throttle behavior. Today […]

Application Security Report: Q2 2023

Cloudflare has a unique vantage point on the Internet. From this position, we are able to see, explore, and identify trends that would otherwise go unnoticed. In this report we are doing just that and sharing our insights into Internet-wide application security trends. This report is the third edition of our Application Security Report. The […]

Unmasking the top exploited vulnerabilities of 2022

The Cybersecurity and Infrastructure Security Agency (CISA) just released a report highlighting the most commonly exploited vulnerabilities of 2022. With our role as a reverse proxy to a large portion of the Internet, Cloudflare is in a unique position to observe how the Common Vulnerabilities and Exposures (CVEs) mentioned by CISA are being exploited on […]

Announcing WAF Attack Score Lite and Security Analytics for business customers

In December 2022 we announced the general availability of the WAF Attack Score. The initial release was for our Enterprise customers, but we always had the belief that this product should be enabled for more users. Today we’re announcing “WAF Attack Score Lite” and “Security Analytics” for our Business plan customers. Looking back on “What […]

The state of application security in 2023

One year ago we published our first Application Security Report. For Security Week 2023, we are providing updated insights and trends around mitigated traffic, bot and API traffic, and account takeover attacks. Cloudflare has grown significantly over the last year. In February 2023, Netcraft noted that Cloudflare had become the most commonly used web server […]

Large CCTV Botnet Leveraged in DDoS Attacks

Our security operations team investigate and mitigate multiple denial of service (DDoS) attacks every single day. One recent case caught our attention because of the intensity and duration of the attack, and – as we discovered through some research – how it was being done. In this article, we’ll share the specifics in an effort to track… […]