UBUNTU-CVE-2025-67726

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Source
https://ubuntu.com/security/CVE-2025-67726
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-67726.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2025-67726
Upstream
Downstream
Related
Published
2025-12-12T07:15:00Z
Modified
2026-01-14T03:21:05.851454Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

Tornado is a Python web framework and asynchronous networking library. Versions 6.5.2 and below use an inefficient algorithm when parsing parameters for HTTP header values, potentially causing a DoS. The _parseparam function in httputil.py is used to parse specific HTTP header values, such as those in multipart/form-data and repeatedly calls string.count() within a nested loop while processing quoted semicolons. If an attacker sends a request with a large number of maliciously crafted parameters in a Content-Disposition header, the server's CPU usage increases quadratically (O(n²)) during parsing. Due to Tornado's single event loop architecture, a single malicious request can cause the entire server to become unresponsive for an extended period. This issue is fixed in version 6.5.3.

References

Affected packages

Ubuntu:24.04:LTS

python-tornado

Package

Name
python-tornado
Purl
pkg:deb/ubuntu/python-tornado@6.4.0-1ubuntu0.4?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
6.4.0-1ubuntu0.4

Affected versions

6.*

6.3.2-1
6.4.0-0ubuntu1
6.4.0-1
6.4.0-1build1
6.4.0-1ubuntu0.1
6.4.0-1ubuntu0.2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python3-tornado",
            "binary_version": "6.4.0-1ubuntu0.4"
        }
    ],
    "availability": "No subscription required"
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-67726.json"

Ubuntu:25.04

python-tornado

Package

Name
python-tornado
Purl
pkg:deb/ubuntu/python-tornado@6.4.2-1ubuntu0.25.04.3?arch=source&distro=plucky

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
6.4.2-1ubuntu0.25.04.3

Affected versions

6.*

6.4.1-2
6.4.1-3
6.4.2-1
6.4.2-1ubuntu0.25.04.1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python3-tornado",
            "binary_version": "6.4.2-1ubuntu0.25.04.3"
        }
    ],
    "availability": "No subscription required"
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-67726.json"

Ubuntu:25.10

python-tornado

Package

Name
python-tornado
Purl
pkg:deb/ubuntu/python-tornado@6.4.2-3ubuntu0.2?arch=source&distro=questing

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
6.4.2-3ubuntu0.2

Affected versions

6.*

6.4.2-1
6.4.2-2
6.4.2-2ubuntu1
6.4.2-3

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python3-tornado",
            "binary_version": "6.4.2-3ubuntu0.2"
        }
    ],
    "availability": "No subscription required"
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-67726.json"

Ubuntu:Pro:16.04:LTS

python-tornado

Package

Name
python-tornado
Purl
pkg:deb/ubuntu/python-tornado@4.2.1-1ubuntu3.1+esm2?arch=source&distro=esm-infra/xenial

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
4.2.1-1ubuntu3.1+esm2

Affected versions

4.*

4.2.1-1ubuntu2
4.2.1-1ubuntu3
4.2.1-1ubuntu3.1
4.2.1-1ubuntu3.1+esm1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python-tornado",
            "binary_version": "4.2.1-1ubuntu3.1+esm2"
        },
        {
            "binary_name": "python3-tornado",
            "binary_version": "4.2.1-1ubuntu3.1+esm2"
        }
    ],
    "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro"
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-67726.json"

Ubuntu:Pro:18.04:LTS

python-tornado

Package

Name
python-tornado
Purl
pkg:deb/ubuntu/python-tornado@4.5.3-1ubuntu0.2+esm2?arch=source&distro=esm-apps/bionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
4.5.3-1ubuntu0.2+esm2

Affected versions

4.*

4.5.1-2.1~build2
4.5.2-1
4.5.3-1
4.5.3-1ubuntu0.1
4.5.3-1ubuntu0.2
4.5.3-1ubuntu0.2+esm1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python-tornado",
            "binary_version": "4.5.3-1ubuntu0.2+esm2"
        },
        {
            "binary_name": "python3-tornado",
            "binary_version": "4.5.3-1ubuntu0.2+esm2"
        }
    ],
    "availability": "Available with Ubuntu Pro: https://ubuntu.com/pro"
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-67726.json"

Ubuntu:Pro:20.04:LTS

python-tornado

Package

Name
python-tornado
Purl
pkg:deb/ubuntu/python-tornado@6.0.3+really5.1.1-3ubuntu0.1~esm3?arch=source&distro=esm-apps/focal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
6.0.3+really5.1.1-3ubuntu0.1~esm3

Affected versions

5.*

5.1.1-4ubuntu1
5.1.1-4ubuntu5

6.*

6.0.3+really5.1.1-2
6.0.3+really5.1.1-2build1
6.0.3+really5.1.1-2build2
6.0.3+really5.1.1-3
6.0.3+really5.1.1-3ubuntu0.1~esm1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python3-tornado",
            "binary_version": "6.0.3+really5.1.1-3ubuntu0.1~esm3"
        }
    ],
    "availability": "Available with Ubuntu Pro: https://ubuntu.com/pro"
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-67726.json"

Ubuntu:Pro:22.04:LTS

python-tornado

Package

Name
python-tornado
Purl
pkg:deb/ubuntu/python-tornado@6.1.0-3ubuntu0.1~esm4?arch=source&distro=esm-apps/jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
6.1.0-3ubuntu0.1~esm4

Affected versions

6.*

6.1.0-1build1
6.1.0-2
6.1.0-3
6.1.0-3build1
6.1.0-3ubuntu0.1~esm1
6.1.0-3ubuntu0.1~esm2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "python3-tornado",
            "binary_version": "6.1.0-3ubuntu0.1~esm4"
        }
    ],
    "availability": "Available with Ubuntu Pro: https://ubuntu.com/pro"
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-67726.json"