Vulnerability Description
Tornado is a Python web framework and asynchronous networking library. Prior to 6.6, Tornado's HTTP header parser accepts obsolete line folding and repeatedly concatenates short continuation lines, causing quadratic CPU consumption on the IOLoop thread. An unauthenticated client can submit a header block containing many obsolete line-folding continuations before application code runs, blocking other connections served by the process. The cost grows with max_header_size, and only availability is affected. This issue is fixed in version 6.6.
CVSS Score
MEDIUM
Related Weaknesses (CWE)
References
- https://github.com/tornadoweb/tornado/commit/1b7a1dc9f340f52de929852e8125aa12f25
- https://github.com/tornadoweb/tornado/pull/3765
- https://github.com/tornadoweb/tornado/releases/tag/v6.6.0
- https://github.com/tornadoweb/tornado/security/advisories/GHSA-pcg2-g6cj-q92c
FAQ
What is CVE-2026-116577?
CVE-2026-116577 is a vulnerability with a CVSS score of 5.3 (MEDIUM). Tornado is a Python web framework and asynchronous networking library. Prior to 6.6, Tornado's HTTP header parser accepts obsolete line folding and repeatedly concatenates short continuation lines, ca...
How severe is CVE-2026-116577?
CVE-2026-116577 has been rated MEDIUM with a CVSS base score of 5.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-116577?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.