{"cve":"CVE-2026-103261","nvd":{"published":"2026-10-01T11:17:20.847","modified":"2026-10-01T15:17:26.580","status":"Deferred","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":{"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","score":6.9},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":5.3},"cwes":["CWE-770"],"references":["https://github.com/tornadoweb/tornado/commit/03945136ea9746eccf61caf88edae39642e59c93","https://github.com/tornadoweb/tornado/security/advisories/GHSA-3hv7-mjh2-fv65","https://www.vulncheck.com/advisories/tornado-before-6.5.9-denial-of-service-via-query-string"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:57:46.668721662+00:00"},"epss":{"cve":"CVE-2026-103261","score":0.00467,"percentile":0.40167,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-3hv7-mjh2-fv65","url":"https://osv.dev/vulnerability/GHSA-3hv7-mjh2-fv65","summary":"Tornado: Unbounded query-string argument count allows event-loop-stalling DoS","modified":"2026-10-02T03:56:09.601689224Z","packages":[{"ecosystem":"PyPI","name":"tornado","purl":"pkg:pypi/tornado","ranges":["<6.5.9"],"fixed":["6.5.9"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}