CVE-2026-103261

medium

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…

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

5.3

5.3 (CVSS v3.1)

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

Severity source: NVD CVSS v3.1 (disclosure@vulncheck.com)

Timeline (UTC)

Published: 2026-10-01 11:17

Modified: 2026-10-01 15:17

NVD status: Deferred

Last synced 2 days ago

Verified against the source API 2026-10-27 06:56 UTC

Exploitation

Not listed in CISA KEV (as of last catalog sync)

Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

Not reported by the source (unknown — not "none").

Weakness classification (CWE)

CWE-770

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

No vendor advisory or patch reference tagged by NVD. Check the references below.

References

https://github.com/tornadoweb/tornado/commit/03945136ea9746eccf61caf88edae39642e59c93 disclosure@vulncheck.com
https://github.com/tornadoweb/tornado/security/advisories/GHSA-3hv7-mjh2-fv65 disclosure@vulncheck.com
https://www.vulncheck.com/advisories/tornado-before-6.5.9-denial-of-service-via-query-stri... disclosure@vulncheck.com

Data sources

NVD CVE API 2.0 — fetched 2026-10-27 06:56 UTC · record ↗

Learn the basics

Understanding CVEs and CVSS Scores