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GHSA-JHMP-MQWM-3GQ8
Vulnerability from github – Published: 2026-07-20 18:57 – Updated: 2026-07-20 18:57
VLAI
Summary
Tornado: Quadratic DoS via Crafted Multipart Parameters
Details
Summary
The _parseparam function in Tornado's httputil.py is used to parse specific HTTP header values, such as those in multipart/form-data. This function uses an inefficient algorithm that repeatedly calls string.count() within a nested loop while processing quoted semicolons (e.g., param=";").
As a result, 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, leading to a Denial of Service (DoS).
Severity: High
Severity
7.5 (High)
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "tornado"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "6.5.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2025-67726"
],
"database_specific": {
"cwe_ids": [
"CWE-400"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-20T18:57:54Z",
"nvd_published_at": "2025-12-12T07:15:44Z",
"severity": "HIGH"
},
"details": "## Summary\n\nThe `_parseparam` function in Tornado\u0027s `httputil.py` is used to parse specific HTTP header values, such as those in `multipart/form-data`. This function uses an inefficient algorithm that repeatedly calls `string.count()` within a nested loop while processing quoted semicolons (e.g., `param=\";\"`).\n\nAs a result, if an attacker sends a request with a large number of maliciously crafted parameters in a `Content-Disposition` header, the server\u0027s CPU usage increases quadratically (O(n\u00b2)) during parsing. Due to Tornado\u0027s single event loop architecture, a single malicious request can cause the entire server to become unresponsive for an extended period, leading to a Denial of Service (DoS).\n\n**Severity: High**",
"id": "GHSA-jhmp-mqwm-3gq8",
"modified": "2026-07-20T18:57:54Z",
"published": "2026-07-20T18:57:54Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-jhmp-mqwm-3gq8"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-67726"
},
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/commit/771472cfdaeebc0d89a9cc46e249f8891a6b29cd"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/tornado/PYSEC-2025-267.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/tornadoweb/tornado"
},
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/releases/tag/v6.5.3"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Tornado: Quadratic DoS via Crafted Multipart Parameters"
}
BREW-JUPYTERLAB-CVE-2025-67726 (GHSA-JHMP-MQWM-3GQ8)
Vulnerability from osv_homebrew – Published: 2026-08-13 17:01 – Updated: 2026-09-25 10:03 – Source website
VLAI
Summary
Tornado: Quadratic DoS via Crafted Multipart Parameters
Details
Summary
The _parseparam function in Tornado's httputil.py is used to parse specific HTTP header values, such as those in multipart/form-data. This function uses an inefficient algorithm that repeatedly calls string.count() within a nested loop while processing quoted semicolons (e.g., param=";").
As a result, 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, leading to a Denial of Service (DoS).
Severity: High
Severity
7.5 (High)
References
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "tornado",
"resource_purl": "pkg:pypi/tornado@6.5.10",
"upstream_fixed_in": "6.5.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "jupyterlab",
"purl": "pkg:brew/jupyterlab"
},
"ranges": [
{
"events": [
{
"introduced": "1.2.0"
},
{
"fixed": "4.5.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/tornado@6.5.10",
"name": "tornado",
"resource": "tornado",
"strategy": "registry",
"subject_version": "6.5.10"
}
]
},
"details": "## Summary\n\nThe `_parseparam` function in Tornado\u0027s `httputil.py` is used to parse specific HTTP header values, such as those in `multipart/form-data`. This function uses an inefficient algorithm that repeatedly calls `string.count()` within a nested loop while processing quoted semicolons (e.g., `param=\";\"`).\n\nAs a result, if an attacker sends a request with a large number of maliciously crafted parameters in a `Content-Disposition` header, the server\u0027s CPU usage increases quadratically (O(n\u00b2)) during parsing. Due to Tornado\u0027s single event loop architecture, a single malicious request can cause the entire server to become unresponsive for an extended period, leading to a Denial of Service (DoS).\n\n**Severity: High**",
"id": "BREW-jupyterlab-CVE-2025-67726",
"modified": "2026-09-25T10:03:06Z",
"published": "2026-08-13T17:01:18Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-jhmp-mqwm-3gq8"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-67726"
},
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/commit/771472cfdaeebc0d89a9cc46e249f8891a6b29cd"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/tornado/PYSEC-2025-267.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/tornadoweb/tornado"
},
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/releases/tag/v6.5.3"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Tornado: Quadratic DoS via Crafted Multipart Parameters",
"upstream": [
"GHSA-jhmp-mqwm-3gq8",
"CVE-2025-67726",
"PYSEC-2025-267"
]
}
BREW-LIVERELOAD-CVE-2025-67726 (GHSA-JHMP-MQWM-3GQ8)
Vulnerability from osv_homebrew – Published: 2026-08-13 17:02 – Updated: 2026-09-10 00:20 – Source website
VLAI
Summary
Tornado: Quadratic DoS via Crafted Multipart Parameters
Details
Summary
The _parseparam function in Tornado's httputil.py is used to parse specific HTTP header values, such as those in multipart/form-data. This function uses an inefficient algorithm that repeatedly calls string.count() within a nested loop while processing quoted semicolons (e.g., param=";").
As a result, 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, leading to a Denial of Service (DoS).
Severity: High
Severity
7.5 (High)
References
| URL | Type | |||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "tornado",
"resource_purl": "pkg:pypi/tornado@6.5.8",
"upstream_fixed_in": "6.5.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "livereload",
"purl": "pkg:brew/livereload"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.7.1_2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/tornado@6.5.8",
"name": "tornado",
"resource": "tornado",
"strategy": "registry",
"subject_version": "6.5.8"
}
]
},
"details": "## Summary\n\nThe `_parseparam` function in Tornado\u0027s `httputil.py` is used to parse specific HTTP header values, such as those in `multipart/form-data`. This function uses an inefficient algorithm that repeatedly calls `string.count()` within a nested loop while processing quoted semicolons (e.g., `param=\";\"`).\n\nAs a result, if an attacker sends a request with a large number of maliciously crafted parameters in a `Content-Disposition` header, the server\u0027s CPU usage increases quadratically (O(n\u00b2)) during parsing. Due to Tornado\u0027s single event loop architecture, a single malicious request can cause the entire server to become unresponsive for an extended period, leading to a Denial of Service (DoS).\n\n**Severity: High**",
"id": "BREW-livereload-CVE-2025-67726",
"modified": "2026-09-10T00:20:41Z",
"published": "2026-08-13T17:02:57Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-jhmp-mqwm-3gq8"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-67726"
},
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/commit/771472cfdaeebc0d89a9cc46e249f8891a6b29cd"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/tornado/PYSEC-2025-267.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/tornadoweb/tornado"
},
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/releases/tag/v6.5.3"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Tornado: Quadratic DoS via Crafted Multipart Parameters",
"upstream": [
"GHSA-jhmp-mqwm-3gq8",
"CVE-2025-67726",
"PYSEC-2025-267"
]
}
BREW-NVCHECKER-CVE-2025-67726 (GHSA-JHMP-MQWM-3GQ8)
Vulnerability from osv_homebrew – Published: 2026-08-13 17:19 – Updated: 2026-10-04 11:16 – Source website
VLAI
Summary
Tornado: Quadratic DoS via Crafted Multipart Parameters
Details
Summary
The _parseparam function in Tornado's httputil.py is used to parse specific HTTP header values, such as those in multipart/form-data. This function uses an inefficient algorithm that repeatedly calls string.count() within a nested loop while processing quoted semicolons (e.g., param=";").
As a result, 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, leading to a Denial of Service (DoS).
Severity: High
Severity
7.5 (High)
References
| URL | Type | |||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "tornado",
"resource_purl": "pkg:pypi/tornado@6.5.10",
"upstream_fixed_in": "6.5.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "nvchecker",
"purl": "pkg:brew/nvchecker"
},
"ranges": [
{
"events": [
{
"introduced": "2.7"
},
{
"fixed": "2.20"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/tornado@6.5.10",
"name": "tornado",
"resource": "tornado",
"strategy": "registry",
"subject_version": "6.5.10"
}
]
},
"details": "## Summary\n\nThe `_parseparam` function in Tornado\u0027s `httputil.py` is used to parse specific HTTP header values, such as those in `multipart/form-data`. This function uses an inefficient algorithm that repeatedly calls `string.count()` within a nested loop while processing quoted semicolons (e.g., `param=\";\"`).\n\nAs a result, if an attacker sends a request with a large number of maliciously crafted parameters in a `Content-Disposition` header, the server\u0027s CPU usage increases quadratically (O(n\u00b2)) during parsing. Due to Tornado\u0027s single event loop architecture, a single malicious request can cause the entire server to become unresponsive for an extended period, leading to a Denial of Service (DoS).\n\n**Severity: High**",
"id": "BREW-nvchecker-CVE-2025-67726",
"modified": "2026-10-04T11:16:44Z",
"published": "2026-08-13T17:19:21Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-jhmp-mqwm-3gq8"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-67726"
},
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/commit/771472cfdaeebc0d89a9cc46e249f8891a6b29cd"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/tornado/PYSEC-2025-267.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/tornadoweb/tornado"
},
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/releases/tag/v6.5.3"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Tornado: Quadratic DoS via Crafted Multipart Parameters",
"upstream": [
"GHSA-jhmp-mqwm-3gq8",
"CVE-2025-67726",
"PYSEC-2025-267"
]
}
BREW-SICKCHILL-CVE-2025-67726 (GHSA-JHMP-MQWM-3GQ8)
Vulnerability from osv_homebrew – Published: 2026-08-13 17:34 – Updated: 2026-09-30 19:29 – Source website
VLAI
Summary
Tornado: Quadratic DoS via Crafted Multipart Parameters
Details
Summary
The _parseparam function in Tornado's httputil.py is used to parse specific HTTP header values, such as those in multipart/form-data. This function uses an inefficient algorithm that repeatedly calls string.count() within a nested loop while processing quoted semicolons (e.g., param=";").
As a result, 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, leading to a Denial of Service (DoS).
Severity: High
Severity
7.5 (High)
References
| URL | Type | |||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "tornado",
"resource_purl": "pkg:pypi/tornado@6.5.10",
"upstream_fixed_in": "6.5.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "sickchill",
"purl": "pkg:brew/sickchill"
},
"ranges": [
{
"events": [
{
"introduced": "2023.5.30"
},
{
"fixed": "2024.3.1_5"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/tornado@6.5.10",
"name": "tornado",
"resource": "tornado",
"strategy": "registry",
"subject_version": "6.5.10"
}
]
},
"details": "## Summary\n\nThe `_parseparam` function in Tornado\u0027s `httputil.py` is used to parse specific HTTP header values, such as those in `multipart/form-data`. This function uses an inefficient algorithm that repeatedly calls `string.count()` within a nested loop while processing quoted semicolons (e.g., `param=\";\"`).\n\nAs a result, if an attacker sends a request with a large number of maliciously crafted parameters in a `Content-Disposition` header, the server\u0027s CPU usage increases quadratically (O(n\u00b2)) during parsing. Due to Tornado\u0027s single event loop architecture, a single malicious request can cause the entire server to become unresponsive for an extended period, leading to a Denial of Service (DoS).\n\n**Severity: High**",
"id": "BREW-sickchill-CVE-2025-67726",
"modified": "2026-09-30T19:29:04Z",
"published": "2026-08-13T17:34:39Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-jhmp-mqwm-3gq8"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-67726"
},
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/commit/771472cfdaeebc0d89a9cc46e249f8891a6b29cd"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/tornado/PYSEC-2025-267.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/tornadoweb/tornado"
},
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/releases/tag/v6.5.3"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Tornado: Quadratic DoS via Crafted Multipart Parameters",
"upstream": [
"GHSA-jhmp-mqwm-3gq8",
"CVE-2025-67726",
"PYSEC-2025-267"
]
}
BREW-SNAKEVIZ-CVE-2025-67726 (GHSA-JHMP-MQWM-3GQ8)
Vulnerability from osv_homebrew – Published: 2026-08-13 17:34 – Updated: 2026-10-04 23:13 – Source website
VLAI
Summary
Tornado: Quadratic DoS via Crafted Multipart Parameters
Details
Summary
The _parseparam function in Tornado's httputil.py is used to parse specific HTTP header values, such as those in multipart/form-data. This function uses an inefficient algorithm that repeatedly calls string.count() within a nested loop while processing quoted semicolons (e.g., param=";").
As a result, 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, leading to a Denial of Service (DoS).
Severity: High
Severity
7.5 (High)
References
| URL | Type | |||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "tornado",
"resource_purl": "pkg:pypi/tornado@6.5.10",
"upstream_fixed_in": "6.5.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "snakeviz",
"purl": "pkg:brew/snakeviz"
},
"ranges": [
{
"events": [
{
"introduced": "2.2.0"
},
{
"fixed": "2.2.2_3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/tornado@6.5.10",
"name": "tornado",
"resource": "tornado",
"strategy": "registry",
"subject_version": "6.5.10"
}
]
},
"details": "## Summary\n\nThe `_parseparam` function in Tornado\u0027s `httputil.py` is used to parse specific HTTP header values, such as those in `multipart/form-data`. This function uses an inefficient algorithm that repeatedly calls `string.count()` within a nested loop while processing quoted semicolons (e.g., `param=\";\"`).\n\nAs a result, if an attacker sends a request with a large number of maliciously crafted parameters in a `Content-Disposition` header, the server\u0027s CPU usage increases quadratically (O(n\u00b2)) during parsing. Due to Tornado\u0027s single event loop architecture, a single malicious request can cause the entire server to become unresponsive for an extended period, leading to a Denial of Service (DoS).\n\n**Severity: High**",
"id": "BREW-snakeviz-CVE-2025-67726",
"modified": "2026-10-04T23:13:43Z",
"published": "2026-08-13T17:34:42Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-jhmp-mqwm-3gq8"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-67726"
},
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/commit/771472cfdaeebc0d89a9cc46e249f8891a6b29cd"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/tornado/PYSEC-2025-267.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/tornadoweb/tornado"
},
{
"type": "WEB",
"url": "https://github.com/tornadoweb/tornado/releases/tag/v6.5.3"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Tornado: Quadratic DoS via Crafted Multipart Parameters",
"upstream": [
"GHSA-jhmp-mqwm-3gq8",
"CVE-2025-67726",
"PYSEC-2025-267"
]
}
CVE-2025-67726 (GCVE-0-2025-67726)
Vulnerability from cvelistv5 – Published: 2025-12-12 06:13 – Updated: 2025-12-18 18:48
VLAI
EPSS
VEX
Title
Tornado is Vulnerable to Quadratic DoS via Crafted Multipart Parameters
Summary
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.
Severity
7.5 (High)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-12-18 18:47 UTC
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/tornadoweb/tornado/security/ad… | x_refsource_CONFIRM |
| https://github.com/tornadoweb/tornado/commit/7714… | x_refsource_MISC |
| https://github.com/tornadoweb/tornado/releases/ta… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| tornadoweb | tornado |
Affected:
< 6.5.3
|
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"value": "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\u0027s CPU usage increases quadratically (O(n\u00b2)) during parsing. Due to Tornado\u0027s 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."
}
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"metrics": [
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"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 7.5,
"baseSeverity": "HIGH",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
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"state": "PUBLISHED"
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PYSEC-2025-267
Vulnerability from pysec - Published: 2025-12-12 07:15 - Updated: 2026-07-13 05:52
VLAI
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.
Severity
7.5 (High)
Impacted products
| Name | purl | tornado | pkg:pypi/tornado |
|---|
Aliases
{
"affected": [
{
"ecosystem_specific": {},
"package": {
"ecosystem": "PyPI",
"name": "tornado",
"purl": "pkg:pypi/tornado"
},
"ranges": [
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"events": [
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"introduced": "0"
},
{
"fixed": "6.5.3"
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"versions": [
"0.2",
"1.0",
"1.1",
"1.1.1",
"1.2",
"1.2.1",
"2.0",
"2.1",
"2.1.1",
"2.2",
"2.2.1",
"2.3",
"2.4",
"2.4.1",
"3.0",
"3.0.1",
"3.0.2",
"3.1",
"3.1.1",
"3.2",
"3.2.1",
"3.2.2",
"4.0",
"4.0.1",
"4.0.2",
"4.1",
"4.1b2",
"4.2",
"4.2.1",
"4.2b1",
"4.3",
"4.3b1",
"4.3b2",
"4.4",
"4.4.1",
"4.4.2",
"4.4.3",
"4.4b1",
"4.5",
"4.5.1",
"4.5.2",
"4.5.3",
"4.5b1",
"4.5b2",
"5.0",
"5.0.1",
"5.0.2",
"5.0a1",
"5.0b1",
"5.1",
"5.1.1",
"5.1b1",
"6.0",
"6.0.1",
"6.0.2",
"6.0.3",
"6.0.4",
"6.0a1",
"6.0b1",
"6.1",
"6.1b1",
"6.1b2",
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"6.2b1",
"6.2b2",
"6.3",
"6.3.1",
"6.3.2",
"6.3.3",
"6.3b1",
"6.4",
"6.4.1",
"6.4.2",
"6.4b1",
"6.5",
"6.5.1",
"6.5.2",
"6.5b1"
]
}
],
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"CVE-2025-67726",
"GHSA-jhmp-mqwm-3gq8"
],
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"id": "PYSEC-2025-267",
"modified": "2026-07-13T05:52:14.026213Z",
"published": "2025-12-12T07:15:44.920Z",
"references": [
{
"type": "ADVISORY",
"url": "https://github.com/tornadoweb/tornado/releases/tag/v6.5.3"
},
{
"type": "ADVISORY",
"url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-jhmp-mqwm-3gq8"
},
{
"type": "FIX",
"url": "https://github.com/tornadoweb/tornado/commit/771472cfdaeebc0d89a9cc46e249f8891a6b29cd"
}
],
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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Trend slope:
-
(linear fit over daily sighting counts)
Show additional events:
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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