CVE-2026-66729
HIGHfacil.io 0.6.0 - 0.7.6 Integer Underflow DoS via Multipart MIME Body Parser
Title source: cnaExploitation Summary
EIP tracks 1 public exploit for CVE-2026-66729. PoCs published by theopaid.
AI-analyzed exploit summary A uint32_t underflow in facil.io's MIME parser (CVE-2026-66729) causes an out-of-bounds read when processing a malformed `Content-Disposition` header with an empty field name (`name=;`). This leads to a server crash due to a 4GB out-of-bounds memory access.
Description
facil.io 0.6.0 through 0.7.6 contains an integer underflow vulnerability in the multipart MIME body parser that allows unauthenticated remote attackers to crash the server process by sending a crafted Content-Disposition header with an empty field name. Attackers can trigger a uint32_t wraparound in http_mime_parser.h causing an out-of-bounds memory read past the name pointer, resulting in a bus fault that crashes the handling worker with a single POST request.
Exploits (1)
A uint32_t underflow in facil.io's MIME parser (CVE-2026-66729) causes an out-of-bounds read when processing a malformed `Content-Disposition` header with an empty field name (`name=;`). This leads to a server crash due to a 4GB out-of-bounds memory access.
References (2)
Scores
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H