CVE-2026-103261 PUBLISHED

Tornado before 6.5.9 Denial of Service via Query String

Assigner: VulnCheck
Reserved: 30.09.2026 Published: 01.10.2026 Updated: 01.10.2026

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.

CVSS 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
CVSS Score: 6.9

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	None	Availability	Low	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS Score: 5.3

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	Low

CVSS 3.1

Product Status

Vendor	tornadoweb
Product	tornado
Versions	Default: unaffected affected from 0 to 6.5.9 (excl.) Version 6.5.9 is unaffected

CVE-2026-103261 PUBLISHED

Tornado before 6.5.9 Denial of Service via Query String

Metrics

Product Status

Credits

References

Problem Types