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CVE-2025-67724

Tornado vulnerable to Header Injection and XSS via reason argument

Published: Dec 12, 2025Updated: Dec 22, 2025 Sources: CVE List NVDCWE-79
NVD MITRE
5.4CVSSMEDIUM
EPSS Score
0.2%
Top 91.9%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

Tornado is a Python web framework and asynchronous networking library. In versions 6.5.2 and below, the supplied reason phrase is used unescaped in HTTP headers (where it could be used for header injection) or in HTML in the default error page (where it could be used for XSS) and can be exploited by passing untrusted or malicious data into the reason argument. Used by both RequestHandler.set_status and tornado.web.HTTPError, the argument is designed to allow applications to pass custom "reason" phrases (the "Not Found" in HTTP/1.1 404 Not Found) to the HTTP status line (mainly for non-standard status codes). This issue is fixed in version 6.5.3.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:RS:UC:LI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:LConfidentiality
Low
I:LIntegrity
Low
A:NAvailability
None
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Weaknesses

CWE-79CWE-644

Affected Products

tornadotornadoweb
Library
OSS Libraries / web-framework
tornadoweboss-projectOSS Librariesaka tornado

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available
Workaround Available

MITRE ATT&CK

2 techniques
Execution
Initial Access
View detailed technique mapping

References

https://github.com/tornadoweb/tornado/security/advisories/GHSA-pr2v-jx2c-wg9f
github.com
https://github.com/tornadoweb/tornado/commit/9c163aebeaad9e6e7d28bac1f33580eb00b0e421
github.com
https://github.com/tornadoweb/tornado/releases/tag/v6.5.3
github.com

Timeline

Published
Dec 12, 2025
Last Updated
Dec 22, 2025

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