Denial-of-Service Vulnerability in facil.io by Facil
CVE-2026-66730

8.7HIGH

Key Information:

Vendor

Boazsegev

Status
Facil.io
Vendor
CVE Published:
27 July 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-66730?

The facil.io framework versions 0.6.0 to 0.7.6 contain a vulnerability in the multipart body parser that can lead to a denial-of-service condition. An unauthenticated remote attacker can exploit this flaw by sending specially crafted multipart/form-data requests with a partial closing boundary. This causes the parser to loop indefinitely without consuming data, which results in all worker processes reaching 100% CPU utilization. Consequently, the affected server may become unresponsive and require a manual restart to restore functionality.

Affected Version(s)

facil.io 0.6.0 <= 0.7.6

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-66730 - Proof of Concept

References

https://github.com/theopaid/Infinite-Loop-DoS-in-facil.io...
technical-descriptionexploit
https://www.vulncheck.com/advisories/facil-io-infinite-lo...
third-party-advisory

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Theodosis Paidakis
.