DEBIAN-CVE-2025-67725

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Source
https://security-tracker.debian.org/tracker/CVE-2025-67725
Import Source
https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-67725.json
JSON Data
https://api.osv.dev/v1/vulns/DEBIAN-CVE-2025-67725
Upstream
Published
2025-12-12T06:15:41.380Z
Modified
2026-01-09T03:18:15.018369Z
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
Summary
[none]
Details

Tornado is a Python web framework and asynchronous networking library. In versions 6.5.2 and below, a single maliciously crafted HTTP request can block the server's event loop for an extended period, caused by the HTTPHeaders.add method. The function accumulates values using string concatenation when the same header name is repeated, causing a Denial of Service (DoS). Due to Python string immutability, each concatenation copies the entire string, resulting in O(n²) time complexity. The severity can vary from high if maxheadersize has been increased from its default, to low if it has its default value of 64KB. This issue is fixed in version 6.5.3.

References

Affected packages

Debian:11 / python-tornado

Package

Name
python-tornado
Purl
pkg:deb/debian/python-tornado?arch=source

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

6.*

6.1.0-1
6.1.0-1+deb11u1
6.1.0-1+deb11u2
6.1.0-2
6.1.0-3
6.2.0-1
6.2.0-2
6.2.0-3
6.3.2-1
6.4.0-1
6.4.0-2
6.4.1-1
6.4.1-2
6.4.1-3
6.4.2-1
6.4.2-2
6.4.2-3
6.5.2-1
6.5.2-2
6.5.2-3
6.5.4-0.1

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source

"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-67725.json"

Debian:12 / python-tornado

Package

Name
python-tornado
Purl
pkg:deb/debian/python-tornado?arch=source

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

6.*

6.2.0-3
6.2.0-3+deb12u1
6.2.0-3+deb12u2
6.3.2-1
6.4.0-1
6.4.0-2
6.4.1-1
6.4.1-2
6.4.1-3
6.4.2-1
6.4.2-2
6.4.2-3
6.5.2-1
6.5.2-2
6.5.2-3
6.5.4-0.1

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source

"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-67725.json"

Debian:13 / python-tornado

Package

Name
python-tornado
Purl
pkg:deb/debian/python-tornado?arch=source

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

6.*

6.4.2-3
6.5.2-1
6.5.2-2
6.5.2-3
6.5.4-0.1

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source

"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-67725.json"

Debian:14 / python-tornado

Package

Name
python-tornado
Purl
pkg:deb/debian/python-tornado?arch=source

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
6.5.4-0.1

Affected versions

6.*

6.4.2-3
6.5.2-1
6.5.2-2
6.5.2-3

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source

"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-67725.json"