CVE-2026-103261

EUVD-2026-90655
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
VulnCheckCNA
5.3 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
tornadowebtornado
𝑥
< 6.5.9
CNA
Debian logo
Debian Releases
Debian Product
Codename
python-tornado
bookworm
vulnerable
bookworm (security)
vulnerable
forky
vulnerable
sid
vulnerable
trixie
vulnerable
trixie (security)
vulnerable
Common Weakness Enumeration
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