Vulnerability-Lookup

SUSE-SU-2026:20043-1

Vulnerability from csaf_suse - Published: 2026-01-08 15:48 - Updated: 2026-01-08 15:48

Summary

Security update for python-tornado6

Notes

Title of the patch

Security update for python-tornado6

Description of the patch

This update for python-tornado6 fixes the following issues: - CVE-2025-67724: Fixed missing validation of the supplied reason phrase (bsc#1254903) - CVE-2025-67725: Fixed inefficient algorithm when parsing parameters for HTTP header values (bsc#1254905) - CVE-2025-67726: Fixed Denial of Service (DoS) via maliciously crafted HTTP request caused by the HTTPHeaders.add method (bsc#1254904)

Patchnames

SUSE-SLE-Micro-6.0-549

CSAF 2.0 data is provided by SUSE under the Creative Commons License 4.0 with Attribution (CC-BY-4.0).

JSON

To clipboard

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        }
      ],
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        {
          "category": "general",
          "text": "Tornado is a Python web framework and asynchronous networking library. In versions 6.5.2 and below, the supplied reason phrase is used unescaped in HTTP headers (where it could be used for header injection) or in HTML in the default error page (where it could be used for XSS) and can be exploited by passing untrusted or malicious data into the reason argument. Used by both RequestHandler.set_status and tornado.web.HTTPError, the argument is designed to allow applications to pass custom \"reason\" phrases (the \"Not Found\" in HTTP/1.1 404 Not Found) to the HTTP status line (mainly for non-standard status codes). This issue is fixed in version 6.5.3.",
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            "SUSE Linux Micro 6.0:python311-tornado6-6.4-4.1.x86_64"
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          "text": "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\u0027s 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(n^2) time complexity. The severity can vary from high if max_header_size 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.",
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          "text": "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^2)) 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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            "SUSE Linux Micro 6.0:python311-tornado6-6.4-4.1.x86_64"
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      "title": "CVE-2025-67726"
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  ]
}

CVE-2025-67725 (GCVE-0-2025-67725)

Vulnerability from cvelistv5 – Published: 2025-12-12 05:49 – Updated: 2025-12-18 18:51

Title

Tornado is Vulnerable to Quadratic DoS via Repeated Header Coalescing

Summary

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 max_header_size 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.

Severity ?

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE

CWE-400 - Uncontrolled Resource Consumption

Assigner

GitHub_M

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

	Vendor	Product	Version
	tornadoweb	tornado	Affected: < 6.5.3

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-67725",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-12-18T18:50:52.619221Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-12-18T18:51:00.369Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "tornado",
          "vendor": "tornadoweb",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 6.5.3"
            }
          ]
        }
      ],
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          "value": "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\u0027s 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(n\u00b2) time complexity. The severity can vary from high if max_header_size 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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "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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        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
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      },
      "references": [
        {
          "name": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-c98p-7wgm-6p64",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-c98p-7wgm-6p64"
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        {
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      "source": {
        "advisory": "GHSA-c98p-7wgm-6p64",
        "discovery": "UNKNOWN"
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      "title": "Tornado is Vulnerable to Quadratic DoS via Repeated Header Coalescing"
    }
  },
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    "dateReserved": "2025-12-10T19:25:20.819Z",
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}

CVE-2025-67724 (GCVE-0-2025-67724)

Vulnerability from cvelistv5 – Published: 2025-12-12 05:36 – Updated: 2025-12-18 18:53

Title

Tornado vulnerable to Header Injection and XSS via reason argument

Summary

Tornado is a Python web framework and asynchronous networking library. In versions 6.5.2 and below, the supplied reason phrase is used unescaped in HTTP headers (where it could be used for header injection) or in HTML in the default error page (where it could be used for XSS) and can be exploited by passing untrusted or malicious data into the reason argument. Used by both RequestHandler.set_status and tornado.web.HTTPError, the argument is designed to allow applications to pass custom "reason" phrases (the "Not Found" in HTTP/1.1 404 Not Found) to the HTTP status line (mainly for non-standard status codes). This issue is fixed in version 6.5.3.

Severity ?

5.4 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

CWE

CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-644 - Improper Neutralization of HTTP Headers for Scripting Syntax

Assigner

GitHub_M

References

URL

Tags

	https://github.com/tornadoweb/tornado/security/ad…	x_refsource_CONFIRM
	https://github.com/tornadoweb/tornado/commit/9c16…	x_refsource_MISC
	https://github.com/tornadoweb/tornado/releases/ta…	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	tornadoweb	tornado	Affected: < 6.5.3

Show details on NVD website

JSON

To clipboard

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CVE-2025-67726 (GCVE-0-2025-67726)

Vulnerability from cvelistv5 – Published: 2025-12-12 06:13 – Updated: 2025-12-18 18:48

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)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE

CWE-834 - Excessive Iteration
CWE-400 - Uncontrolled Resource Consumption

Assigner

GitHub_M

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

	Vendor	Product	Version
	tornadoweb	tornado	Affected: < 6.5.3

Show details on NVD website

JSON

To clipboard

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Tags

Taxonomy of the tags.

All sightings related to this event Export sightings related to this event

Sightings

Author	Source	Type	Date

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.

Detection rules are retrieved from Rulezet.

Action not permitted

SUSE-SU-2026:20043-1

CVE-2025-67725 (GCVE-0-2025-67725)

CVE-2025-67724 (GCVE-0-2025-67724)

CVE-2025-67726 (GCVE-0-2025-67726)

Tags

Sightings

Nomenclature