Tornado before 6.5.8 contains an incomplete fix for cookie attribute injection that allows attackers to inject arbitrary cookie attributes by passing capitalized or legacy keyword arguments to set_cookie. Attackers can embed semicolon-delimited data in capitalized parameters like Domain, Path, or SameSite to bypass validation and modify cookie security attributes.

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Fixes

Solution

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Workaround

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History

Tue, 15 Sep 2026 15:30:00 +0000

Type Values Removed Values Added
Description Tornado before 6.5.8 contains an incomplete fix for cookie attribute injection that allows attackers to inject arbitrary cookie attributes by passing capitalized or legacy keyword arguments to set_cookie. Attackers can embed semicolon-delimited data in capitalized parameters like Domain, Path, or SameSite to bypass validation and modify cookie security attributes.
Title Tornado before 6.5.8 Cookie Attribute Injection via Capitalized kwargs
First Time appeared Tornadoweb
Tornadoweb tornado
Weaknesses CWE-113
CPEs cpe:2.3:a:tornadoweb:tornado:*:*:*:*:*:*:*:*
Vendors & Products Tornadoweb
Tornadoweb tornado
References
Metrics cvssV3_1

{'score': 5.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N'}

cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-09-15T15:18:32.408Z

Reserved: 2026-09-15T11:11:13.311Z

Link: CVE-2026-91991

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-15T16:17:58.293

Modified: 2026-09-15T16:17:58.293

Link: CVE-2026-91991

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses