CVE-2026-66729

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.

CVSS Vector

References

• https://github.com/theopaid/Out-of-Bounds-Read-in-facil.io-MIME-Parser-leads-to-Server-Crash
• https://www.vulncheck.com/advisories/facil-io-integer-underflow-dos-via-multipart-mime-body-parser