CVE-2026-66731

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Source

https://cve.org/CVERecord?id=CVE-2026-66731

Import Source

https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-66731.json

JSON Data

https://api.osv.dev/v1/vulns/CVE-2026-66731

Published

2026-07-27T16:57:01Z

Modified

2026-08-12T03:51:47Z

Severity

8.7 (High) CVSS_V4 - 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 CVSS Calculator

Summary

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

Details

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.

Database specific

{
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
        "CWE-125"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66731.json"
}

References

Affected packages

Git / github.com/boazsegev/facil.io

Affected ranges

Type

GIT

Repo

https://github.com/boazsegev/facil.io

Events

Introduced

063c9bb86e14bae7441d2e37ab7207d9839a98ce

Last Affected

512a354dbd31e1895647df852d1565f9d408ed91

Database specific

Show details

{
    "extracted_events": [
        {
            "introduced": "0.7.5"
        },
        {
            "last_affected": "0.7.6"
        }
    ],
    "source": "AFFECTED_FIELD"
}

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-66731.json"