{"id":"CVE-2026-103261","title":"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","summary":"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 unauth…","severity":"medium","cvss":5.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","cwe":["CWE-770"],"vendor":"tornadoweb","product":"tornado","affected":["tornado < 6.5.9"],"published":"2026-10-01","updated":"2026-10-01","sourceUpdated":"2026-10-01T11:17:20.997","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-103261","references":[{"url":"https://github.com/tornadoweb/tornado/commit/03945136ea9746eccf61caf88edae39642e59c93","label":"disclosure@vulncheck.com"},{"url":"https://github.com/tornadoweb/tornado/security/advisories/GHSA-3hv7-mjh2-fv65","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/tornado-before-6.5.9-denial-of-service-via-query-string","label":"disclosure@vulncheck.com"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-10-01T11:42:53.804Z","slug":"CVE-2026-103261","body":"## Overview\n\nTornado 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":29,"depthScoreParts":{"impact":29.2,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}