It was discovered that Tornado incorrectly handled special characters in HTTP headers. An attacker could possibly use this issue to execute a cross- site scripting (XSS) attack. This issue only affected Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, Ubuntu 25.04, and Ubuntu 25.10. ( CVE-2025-67724 ) It was discovered that Tornado incorrectly handled repeated HTTP headers. An attacker could possibly use this issue to cause Tornado to use excessive resources, causing a denial of service. ( CVE-2025-67725 ) It was discovered that Tornado incorrectly handled parsing of certain HTTP header values. An attacker could possibly use this issue to cause Tornado to use excessive resources, causing a denial of service. ( CVE-2025-67726 )
It was discovered that Tornado incorrectly handled special characters in HTTP headers. An attacker could possibly use this issue to execute a cross- site scripting (XSS) attack. This issue only affected Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, Ubuntu 25.04, and Ubuntu 25.10. ( CVE-2025-67724 )
It was discovered that Tornado incorrectly handled repeated HTTP headers. An attacker could possibly use this issue to cause Tornado to use excessive resources, causing a denial of service. ( CVE-2025-67725 )
It was discovered that Tornado incorrectly handled parsing of certain HTTP header values. An attacker could possibly use this issue to cause Tornado to use excessive resources, causing a denial of service. ( CVE-2025-67726 )
It was discovered that Tornado incorrectly handled special characters in HTTP headers. An attacker could possibly use this issue to execute a cross- site scripting (XSS) attack. This issue only affected Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, Ubuntu 25.04, and Ubuntu 25.10. ( CVE-2025-67724 ) It was discovered that Tornado incorrectly handled repeated HTTP headers. An attacker could possibly use this issue to cause Tornado to use excessive resources, causing a denial of service. ( CVE-2025-67725 ) It was discovered that Tornado incorrectly handled parsing of certain HTTP header values. An attacker could possibly use this issue to cause Tornado to use excessive resources, causing a denial of service. ( CVE-2025-67726 )
It was discovered that Tornado incorrectly handled special characters in HTTP headers. An attacker could possibly use this issue to execute a cross- site scripting (XSS) attack. This issue only affected Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, Ubuntu 25.04, and Ubuntu 25.10. ( CVE-2025-67724 )
It was discovered that Tornado incorrectly handled repeated HTTP headers. An attacker could possibly use this issue to cause Tornado to use excessive resources, causing a denial of service. ( CVE-2025-67725 )
It was discovered that Tornado incorrectly handled parsing of certain HTTP header values. An attacker could possibly use this issue to cause Tornado to use excessive resources, causing a denial of service. ( CVE-2025-67726 )
In general, a standard system update will make all the necessary changes.
The problem can be corrected by updating your system to the following package versions:
Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines.
The full story
This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.
