Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
AV AC AT PR UI VC VI VA CVSS EPSS %ile KEV N L N N N N N H 8.7 .0060 45.9 —
AFFECTED Product Versions Fixed facil.io 0.7.5 – —
TIMELINE Jul 27 Reserved by VulnCheck Jul 27 Published (CNA: VulnCheck) Jul 30 EXPLOIT PUBLISHED — CVE-2026-66731 (boazsegev facil.io). Public exploit reference added.
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.
| Date | Event | Detail |
|---|---|---|
| July 27, 2026 | Reserved | Reserved by VulnCheck |
| July 27, 2026 | Published | Published (CNA: VulnCheck) |
| July 30, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-66731 (boazsegev facil.io). Public exploit reference added. |
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|---|---|---|---|
| boazsegev | facil.io | — | 0.7.5 | — |
Authoritative record: CVE-2026-66731 at cve.org
Vendors: boazsegev
Weaknesses: CWE-125
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-66731 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.