CVE-2026-103261

Tornado before 6.5.9 Denial of Service via Query String

Published Oct 1, 2026 CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed
Description
Tornado before 6.5.9 fails to limit the number of query string fields in HTTPServerRequest.__init__, allowing remote attackers to cause event-loop stalling by sending requests with thousands of query parameters. Attackers can send unauthenticated GET requests with unbounded query-string field counts to degrade response times for all clients sharing the same IOLoop.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description Tornado before 6.5.9 fails to limit the number of query string fields in HTTPServerRequest.__init__, allowing remote attackers to cause event-loop stalling by sending requests with thousands of query parameters. Attackers can send unauthenticated GET requests with unbounded query-string field counts to degrade response times for all clients sharing the same IOLoop.
Title Tornado before 6.5.9 Denial of Service via Query String
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': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Oct 1, 2026, 2:44 PM
Reserved
Sep 30, 2026, 10:55 AM
Status
Deferred
Published
Oct 1, 2026, 11:17 AM
Modified
Oct 1, 2026, 3:17 PM
Severity
Moderate
Public date
Oct 1, 2026, 10:42 AM