CVE-2026-91990

Tornado before 6.5.8 Memory Amplification DoS via multipart

Published Sep 15, 2026 CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-8952-1 Tornado vulnerabilities
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title Tornado before 6.5.8 Memory Amplification DoS via multipart
First Time appeared Tornadoweb
Tornadoweb tornado
Weaknesses CWE-770
CPEs cpe:2.3:a:tornadoweb:tornado:*:*:*:*:*:*:*:*
Vendors & Products Tornadoweb
Tornadoweb tornado
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.7, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Sep 15, 2026, 4:05 PM
Reserved
Sep 15, 2026, 11:11 AM
Status
Deferred
Published
Sep 15, 2026, 4:17 PM
Modified
Sep 16, 2026, 1:42 PM
Severity
Important
Public date
Sep 15, 2026, 3:18 PM