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TI-2026-47389 Aliases CVE-2026-66731GHSA-vg6c-748h-g68q

facil.io 0.7.5 - 0.7.6 HTTP/1.1 Chunked Transfer Encoding Parser Crash DoS

Priority HIGH 77CWE-125Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
No fix listed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-125 and the CVSS impact.

Summary

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 send a single POST request with a Transfer-Encoding: chunked header containing a leading minus sign in the chunk size field, causing the parser in http1_parser.h to compute a large positive integer from the negated value, corrupting internal state and moving the read pointer into unmapped memory resulting in a fault.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00784 56th percentileScored 2026-11-07
Public exploit Yes 2 exploit referencesTagged by the CNA
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
boazsegevfacil.io0.7.5 – 0.7.6—No fix listedCNA
  • facil.io Vendorboazsegev Affected 0.7.5 – 0.7.6 Fixed in — No fix listed CNA

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-66731
  2. 2026-10-03 Alias added: GHSA-vg6c-748h-g68q

References

Exploit 2

  • TI-2026-47388 facil.io 0.6.0 - 0.7.6 Infinite Loop DoS via Multipart MIME Body Parser CVSS 4.0HIGH 8.7
  • TI-2026-47387 facil.io 0.6.0 - 0.7.6 Integer Underflow DoS via Multipart MIME Body Parser CVSS 4.0HIGH 8.7
  • TI-2026-29774 Uncontrolled resource consumption in boazsegev facil.io CVSS 4.0HIGH 8.7
  • TI-2026-13899 boazsegev facil.io Public Folder http.c http_sendfile2 path traversal CVSS 4.0MEDIUM 6.9
  • TI-2026-13880 boazsegev facil.io WebSocket Frame websocket_parser.h websocket_on_protocol_error input validation CVSS 4.0MEDIUM 6.9
  • TI-2024-14668 Iodine Static File Server Path Traversal Vulnerability CVSS 3.1HIGH 7.5

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences