SEPTEMBER 20, 2026
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Case File

CVE-2026-66731

HIGH · CVSS 7.5 EPSS 0.60% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-07-27 · Last synced 2026-08-26

CyberRota Analysis

AI-Generated

The vulnerability affects facil.io versions 0.7.5 to 0.7.6, allowing unauthenticated remote attackers to exploit the HTTP/1.1 chunked transfer encoding parser. By sending a specially crafted POST request with a negative chunk size, attackers can trigger a denial-of-service condition, leading to server crashes. Organizations using these specific versions of facil.io should prioritize patching to mitigate potential disruptions.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-66731
Severity
HIGH
CVSS
7.5
EPSS
0.60%

Original NVD Description

facil.io 0.7.5 through 0.7.6 contains a denial-of-service vulnerability in the HTTP/1.1 chunked transfer encoding parser that allows unauthenticated remote attackers to crash the server by sending a negative chunk size value. Attackers can send a single POST request with a Transfer-Encoding: chunked header containing a leading minus sign in the chunk size field, causing the parser in http1_parser.h to compute a large positive integer from the negated value, corrupting internal state and moving the read pointer into unmapped memory resulting in a fault.