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CVE-2026-103261— Tornado before 6.5.9 Denial of Service via Query String

Quick assessment

Affected
tornadoweb tornado
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Tornado 6.5.9 之前的版本未能在 中限制查询字符串字段的数量，使得远程攻击者可以通过发送包含数千个查询参数的请求来导致事件循环（event loop）停滞。攻击者可发送未经身份验证的 GET 请求，其中查询字符串字段数量不受限制，从而降低所有共享同一 IOLoop 的客户端的响应时间。

CVSS 5.3 · Medium

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2026-103261

Vulnerability Information
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Vulnerability Title
Tornado before 6.5.9 Denial of Service via Query String
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
tornadoweb tornado 0 ~ 6.5.9 -

II. Public POCs for CVE-2026-103261

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III. Intelligence Information for CVE-2026-103261

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Other References for CVE-2026-103261 (3)

Same Patch Batch · tornadoweb · 2026-10-01 · 3 CVEs total

CVE-2026-103262 7.5 HIGH Tornado before 6.5.9 Denial of Service via CurlAsyncHTTPClient
CVE-2026-103263 5.9 MEDIUM Tornado before 6.5.9 StaticFileHandler Path Traversal via Symlink

IV. Related Vulnerabilities

Same product: tornado
Same vendor: tornadoweb
Same weakness: CWE-770

V. Comments for CVE-2026-103261

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