python-tornado vulnerabilities

USN-8198-1 fixed vulnerabilities in Tornado. This update provides the
corresponding updates for Ubuntu 26.04 LTS.

Original advisory details:

It was discovered that Tornado incorrectly handled parsing of large
multipart request bodies. An attacker could possibly use this issue to
cause a denial of service. (CVE-2026-31958)

It was discovered that Tornado did not properly validate characters in
cookie values. An attacker could possibly use this issue to inject
arbitrary cookie attributes. (CVE-2026-35536)