CVE-2026-91990 Details
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.
A memory amplification vulnerability leading to denial-of-service has been identified in Tornado versions prior to 6.5.8. The issue arises in the 'parse_multipart_form_data' function, where multipart data is split before checking the maximum allowed parts. This flaw allows attackers to send specially crafted multipart requests with numerous parts, creating large temporary lists that exhaust server memory.
Users are advised to update Tornado to version 6.5.8 or later, where this vulnerability has been patched.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 15, 2026CISA-ADP
Assessed Sep 15, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/tornadoweb/tornado/security/advisories/GHSA-8423-8fgw-73vq | CISA-ADP | AdvisoryExploitRemedyVendor |
| https://github.com/tornadoweb/tornado/security/advisories/GHSA-8423-8fgw-73vq | [email protected] | AdvisoryExploitRemedyVendor |
| https://www.vulncheck.com/advisories/tornado-before-6.5.8-memory-amplification-dos-via-multipart | [email protected] | Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-770 | Allocation of Resources Without Limits or Throttling | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Tornado | <= 6.5.7 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 15, 2026 | CVE Modified | CISA-ADP |
| Sep 15, 2026 | New CVE Received | [email protected] |