CVE-2026-66729 | facil.io 0.6.0 through 0.7.6 contains an integer underflow v… | CVSS 7.5 HIGH

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.

Metadata

CVE ID: CVE-2026-66729
State: PUBLISHED
Assigner: VulnCheck
Reserved: 2026-07-27 16:27 UTC
Published: 2026-07-27 16:52 UTC
Last updated: 2026-07-27 17:54 UTC
Primary CWE: CWE-125
Out-of-bounds Read
Vendor / Product: boazsegev / facil.io
Sources: cve.org · NVD

Severity & Metrics

7.5 HIGH CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC — CISA Coordinator

Exploitation: PoC
Automatable: yes
Tech. Impact: partial

Affected products (1)

Vendor	Product	Platform	Versions
boazsegev	facil.io	—	0.6.0 ≤ 0.7.6

Weakness (CWE)

CWE	Source	Description
CWE-125	cna	Out-of-bounds Read

CVSS scores (2)

Score	Severity	Version	Source	Vector
8.7	HIGH	4.0	cna	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
7.5	HIGH	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References (2)