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CVE-2020-13935 is an uncontrolled resource-consumption vulnerability in Apache Tomcat WebSocket frame parsing. Tomcat failed to correctly validate the payload-length field of an incoming WebSocket frame. A malformed length can cause the affected processing logic to enter an infinite loop. The issue affects Tomcat 7.0.27 through 7.0.104, 8.5.0 through 8.5.56, 9.0.0.M1 through 9.0.36, and 10.0.0-M1 through 10.0.0-M6.
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1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
This repository contains a Go-based proof-of-concept exploit for CVE-2020-13935, a vulnerability in Apache Tomcat's WebSocket implementation. The exploit is implemented in a single file, 'main.go', which constructs and sends malformed WebSocket frames to a user-supplied WebSocket endpoint. By setting all bits of the length field in the WebSocket frame to 1, the exploit triggers a bug in Tomcat that results in continuous high CPU usage on the server. The exploit launches 200 concurrent goroutines, each sending a crafted message and keeping the connection open for 30 seconds, amplifying the impact. The repository is structured simply, with supporting files for Go module management and documentation. No hardcoded endpoints are present; the target is specified at runtime. The exploit is a denial-of-service (DoS) tool and does not provide shell access or code execution.
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18 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A named CVE referenced as a Nuclei denial-of-service detection template with an invalid contributor signature. No technical details of the underlying flaw are provided.
An Apache Tomcat WebSocket denial-of-service vulnerability involving invalid payload lengths.
A denial-of-service vulnerability in Tomcat WebSocket frame processing, triggered by multiple requests containing an invalid payload length.
A denial-of-service vulnerability in Tomcat's WebSocket frame handling, triggered through multiple requests with invalid payload lengths.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.