{"id":"CVE-2026-103261","summary":"Tornado before 6.5.9 Denial of Service via Query String","details":"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.","aliases":["GHSA-3hv7-mjh2-fv65"],"modified":"2026-10-03T03:45:42.530580567Z","published":"2026-10-01T10:42:04.230Z","database_specific":{"cna_assigner":"VulnCheck","cwe_ids":["CWE-770"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/103xxx/CVE-2026-103261.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/103xxx/CVE-2026-103261.json"},{"type":"ADVISORY","url":"https://github.com/tornadoweb/tornado/security/advisories/GHSA-3hv7-mjh2-fv65"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-103261"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/tornado-before-6.5.9-denial-of-service-via-query-string"},{"type":"FIX","url":"https://github.com/tornadoweb/tornado/commit/03945136ea9746eccf61caf88edae39642e59c93"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/tornadoweb/tornado","events":[{"introduced":"0"},{"fixed":"75ef8b1cfa0e658aceb17c5a810ad1c74dc69bc7"},{"fixed":"03945136ea9746eccf61caf88edae39642e59c93"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"6.5.9"}],"source":["DESCRIPTION","REFERENCES"]}}],"versions":["v6.5.8","v6.5.7","v6.5.6","v6.5.5","v6.5.4","v6.5.3","v6.5.2","v6.5.1","v6.5.0","v6.5.0b1","v6.4.1","v6.4.0","v6.4.0b1","v6.3.1","v6.3.0","v6.3.0b1","v6.2.0","v6.2.0b2","v6.2.0b1","v6.1.0","v6.1.0b2","v6.1.0b1","v6.0.0","v6.0.0b1","v5.1.0","v5.0.0","v4.5.0","v4.5.1","v4.4.1","v4.4.0","v4.4.0b1","v4.3.0","v4.3.0b2","v4.3.0b1","v4.2.0","v4.2.0b1","v4.1.0","v4.1.0b2","v4.1.0b1","v4.0.0","v4.0.0b3","v4.0.0b2","v4.0.0b1","v3.2.0","v3.2.0b2","v3.2.0b1","v3.1.0","v3.0.1","v3.0.0","v2.1.1","v2.3.0","v2.2.0","v2.1.0","v2.0.0","v1.2.0","v1.1.0","v1.0.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-103261.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}]}