Memory Amplification Vulnerability in Tornado Web Framework by Tornado
CVE-2026-91990

8.7HIGH

Key Information:

Vendor

Tornadoweb

Status
Tornado
Vendor
CVE Published:
15 September 2026

What is CVE-2026-91990?

The Tornado web framework prior to version 6.5.8 has a memory amplification vulnerability in the parse_multipart_form_data function. This issue arises when multipart data is split without validating the maximum parts limit, enabling attackers to craft malicious multipart requests. By exploiting this flaw, they can create large transient lists that exhaust server memory, potentially leading to denial of service and affecting the overall performance and availability of the services offered by Tornado.

Affected Version(s)

tornado 0 < 6.5.8

tornado 6.5.8

References

https://github.com/tornadoweb/tornado/security/advisories...
vendor-advisory
https://www.vulncheck.com/advisories/tornado-before-6.5.8...
third-party-advisory

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.