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CVE-2026-91990

Tornado before 6.5.8 Memory Amplification DoS via multipart

CVSS 4.0 8.7 HIGHCVSS 3.1 7.5 HIGHCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-91990

Published

Tornado before 6.5.8 contains a memory amplification vulnerability in parse_multipart_form_data that splits multipart data before validating the max_parts limit. Attackers can send crafted multipart requests with many parts to create large transient lists, exhausting server memory and causing denial of service.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-91990

Published

tornado

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "tornadoweb",
                    "product": "tornado",
                    "defaultStatus": "unaffected",
                    "packageURL": "pkg:pypi/tornado",
                    "versions": [
                        {
                            "version": "0",
                            "status": "affected",
                            "versionType": "semver",
                            "lessThan": "6.5.8"
                        },
                        {
                            "version": "6.5.8",
                            "status": "unaffected",
                            "versionType": "semver"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON