Out-of-bounds Read in Boazsegev Facil.io
CVE-2026-66731
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…
Vulnerability class: Buffer Overflow
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Boazsegev Facil.io — versions 0.7.5
Weakness classification (CWE)
Public proof-of-concept exploits
References
- disclosure@vulncheck.com (technical-description, exploit)
- disclosure@vulncheck.com (third-party-advisory)
Frequently asked questions
- What is CVE-2026-66731?
- CVE-2026-66731 is a high-severity vulnerability in Boazsegev Facil.io, classified under Out-of-bounds Read. CVSS score: 7.5/10. Published 2026-07-27.
- How severe is CVE-2026-66731?
- High severity. CVSS v3 base score is 7.5 out of 10.
- Is CVE-2026-66731 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.