CVE-2026-103261: Allocation of Resources Without Limits or Throttling in tornadoweb tornado
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.
AI Analysis
Technical Summary
Tornado versions prior to 6.5.9 do not impose limits on the number of query string fields in HTTPServerRequest.__init__. Remote attackers can exploit this by sending requests containing an unbounded number of query parameters, which leads to resource exhaustion and event-loop stalling. This results in degraded response times affecting all clients using the same IOLoop instance.
Potential Impact
The vulnerability allows unauthenticated remote attackers to degrade the performance of Tornado-based applications by causing event-loop stalling through excessive query parameters. This can lead to denial of service conditions where legitimate client requests experience slow response times.
Mitigation Recommendations
Upgrade Tornado to version 6.5.9 or later where this issue is fixed. No other mitigation or temporary workaround is indicated in the provided data.
CVE-2026-103261: Allocation of Resources Without Limits or Throttling in tornadoweb tornado
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.
CVSS v4.0
Score 6.9medium
Affected software
tornadoweb
tornado
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Tornado versions prior to 6.5.9 do not impose limits on the number of query string fields in HTTPServerRequest.__init__. Remote attackers can exploit this by sending requests containing an unbounded number of query parameters, which leads to resource exhaustion and event-loop stalling. This results in degraded response times affecting all clients using the same IOLoop instance.
Potential Impact
The vulnerability allows unauthenticated remote attackers to degrade the performance of Tornado-based applications by causing event-loop stalling through excessive query parameters. This can lead to denial of service conditions where legitimate client requests experience slow response times.
Mitigation Recommendations
Upgrade Tornado to version 6.5.9 or later where this issue is fixed. No other mitigation or temporary workaround is indicated in the provided data.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-09-30T10:55:39.869Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6abe7494a43b0b3b89bd1cf5
Added to database: 10/01/2026, 14:56:20 UTC
Last enriched: 10/01/2026, 15:07:37 UTC
Last updated: 10/01/2026, 19:41:32 UTC
Views: 3
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