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Ubuntu 25.10: Tornado Critical XSS DoS Flaws USN-7950-1 CVE-2025-67724

ubuntu
Calendar Grey January 8, 2026
Scroller Ubuntu
Multiple Tornado security issues in Ubuntu fixed with immediate package updates required for safety. Key vulnerabilities detailed.
Several security issues were fixed in Tornado.

Summary

Several security issues were fixed in Tornado.

Software Description:

- python-tornado: scalable, non-blocking web server and tools

Details:

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)

Topics%20covered

Topics Covered

security advisory denial of service critical XSS Ubuntu python-tornado

Update Instructions

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 25.10
  python3-tornado                 6.4.2-3ubuntu0.2

Ubuntu 25.04
  python3-tornado                 6.4.2-1ubuntu0.25.04.3

Ubuntu 24.04 LTS
  python3-tornado                 6.4.0-1ubuntu0.4

Ubuntu 22.04 LTS
  python3-tornado                 6.1.0-3ubuntu0.1~esm4
                                  Available with Ubuntu Pro

Ubuntu 20.04 LTS
  python3-tornado                 6.0.3+really5.1.1-3ubuntu0.1~esm3
                                  Available with Ubuntu Pro

Ubuntu 18.04 LTS
  python-tornado                  4.5.3-1ubuntu0.2+esm2
                                  Available with Ubuntu Pro
  python3-tornado                 4.5.3-1ubuntu0.2+esm2
                                  Available with Ubuntu Pro

Ubuntu 16.04 LTS
  python-tornado                  4.2.1-1ubuntu3.1+esm2
                                  Available with Ubuntu Pro
  python3-tornado                 4.2.1-1ubuntu3.1+esm2
                                  Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.

References

https://ubuntu.com/security/notices/USN-7950-1

CVE-2025-67724, CVE-2025-67725, CVE-2025-67726

Severity
critical
Lowest
Low
Medium
High
Critical

Ubuntu Security Notice USN-7950-1

Topics%20covered

Topics Covered

security advisory denial of service critical XSS Ubuntu python-tornado

Package Information

https://launchpad.net/ubuntu/+source/python-tornado/6.4.2-3ubuntu0.2
https://launchpad.net/ubuntu/+source/python-tornado/6.4.2-1ubuntu0.25.04.3
https://launchpad.net/ubuntu/+source/python-tornado/6.4.0-1ubuntu0.4

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