CVE-2026-66729: high-severity vulnerability in boazsegev facil.io
facil.io 0.6.0 - 0.7.6 Integer Underflow DoS via Multipart MIME Body Parser
Published · Updated
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41Vexday Risk Score
No sign of exploitation. It has a public proof of concept.
ssvc Attendcvss 8.7epss 0.8%
from disclosure to weaponsame day
Published on NVDJul 27
1st PoCJul 24
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:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Affected products
boazsegev · facil.iopublic PoCs found — 3
githubgithub.com/theopaid/CVE-2026-66729-Out-of-Bounds-Read-in-facil.io-MIME-Parser-leads-to-Server-Crash★ 1cve_referencegithub.com/theopaid/Out-of-Bounds-Read-in-facil.io-MIME-Parser-leads-to-Server-Crashunverifiedcve_referencetpaidakis.com/writeups/facilio-parser-dos/unverified⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
Related CVEs — boazsegev facil.io
In the same product, most dangerous first.
CVE-2026-66731HIGHfacil.io 0.7.5 - 0.7.6 HTTP/1.1 Chunked Transfer Encoding Parser Crash DoSEPSS 0.8%CVE-2026-66730HIGHfacil.io 0.6.0 - 0.7.6 Infinite Loop DoS via Multipart MIME Body ParserEPSS 0.8%CVE-2026-16653MEDIUMboazsegev facil.io Public Folder http.c http_sendfile2 path traversalEPSS 0.7%CVE-2026-16632MEDIUMboazsegev facil.io WebSocket Frame websocket_parser.h websocket_on_protocol_error input validationEPSS 0.5%CVE-2026-41146HIGHfacil.io and downstream iodine ruby gem vulnerable to uncontrolled resource consumption and loop with unreachable exit conditionEPSS 0.4%