CVE-2026-66731 – facil.io 0.7.5 – 0.7.6 HTTP/1.1 Chunked Transfer Encoding Parser Crash DoS

CVE ID :CVE-2026-66731

Published : July 27, 2026, 5:16 p.m. | 39 minutes ago

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.

Severity: 8.7 | HIGH

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