Tornado before 6.5.9 Denial of Service via Query String
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.
CVE-2026-103261
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-103261
tornado
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"vendor": "tornadoweb",
"product": "tornado",
"versions": [
{
"status": "affected",
"version": "0",
"lessThan": "6.5.9",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.5.9",
"versionType": "semver"
}
],
"packageURL": "pkg:pypi/tornado",
"defaultStatus": "unaffected"
}
]- Related CVEs
- CVE-2026-103261
Source reference:
/cveMetadata/cveId
Publisher severity
medium
Source reference: /containers/cna/metrics
- Event
- #5268 · Revision 1
- Added to Heist Feed
- Publisher date