CVE-2025-47287: Tornado Tornado Vulnerable To Excessive Logging Vulnerability

HIGH
Advisory Identifier: GHSA-7cx3-6m66-7c5m
Share
CVSS 7.5
CWE-770
Published
Advisory Summary

CVE-2025-47287 is a HIGH (CVSS 7.5) tornado vulnerable to excessive logging vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting Tornado libraries in the PyPI ecosystem. The issue involves tornado vulnerable to excessive logging caused by malformed multipart form data. Remediation is available by upgrading affected packages to version 6.5.

CVE-2025-47287 at a Glance

CVE Identifier CVE-2025-47287
GHSA Identifier GHSA-7cx3-6m66-7c5m
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-770: Allocation of Resources Without Limits or Throttling
Affected Product Tornado
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2025-47287

To remediate this vulnerability, upgrade all affected Tornado dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

tornado fixed: 6.5 
pip install tornado>=6.5
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show tornado

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2025-47287, inspect your installed packages using pip:

pip show tornado

Analyze the terminal output to locate any version of Tornado in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 6.5), your application is affected.

Note: The pip show tornado command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-770: Allocation of Resources Without Limits or Throttling, where the product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. In Tornado, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary When Tornado's ``multipart/form-data`` parser encounters certain errors, it logs a warning but continues trying to parse the remainder of the data. This allows remote attackers to generate an extremely high volume of logs, constituting a DoS attack. This DoS is compounded by the fact that the logging subsystem is synchronous. ### Affected versions All versions of Tornado prior to 6.5 are affected. The vulnerable parser is enabled by default. ### Solution Upgrade to Tornado version 6.5. In the meantime, risk can be mitigated by blocking `Content-Type: multipart/form-data` in a proxy.

CVE-2025-47287 Affected Tornado Versions

1 component(s)
Fixed Versions:
6.5
Product / Package Ecosystem Affected Versions Fixed Version
tornado
pypi/tornado
PyPI
< 6.5
6.5

References

GitHub Advisory / Wiki ADVISORY
https://github.com/tornadoweb/tornado/security/advisories/GHSA-7cx3-6m66-7c5m
NVD — CVE-2025-47287 NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-47287
Security Fix Commit FIX COMMIT
https://github.com/tornadoweb/tornado/commit/b39b892bf78fe8fea01dd45199aa88307e7162f3
Tornado Source Repository REPOSITORY
https://github.com/tornadoweb/tornado
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2025/05/msg00038.html

Frequently Asked Questions

What is CVE-2025-47287?
CVE-2025-47287 is a security vulnerability in Tornado involving Tornado vulnerable to excessive logging caused by malformed multipart form data under CWE-770: Allocation of Resources Without Limits or Throttling.
Which Tornado versions are affected?
Affected versions include releases prior to 6.5 across affected packages: tornado.
What version fixes CVE-2025-47287?
Upgrading to 6.5 (or the latest patched release for your respective branch) resolves the vulnerability.
Is tornado affected?
Yes, tornado is affected in releases prior to 6.5. Upgrade your dependency to 6.5 or later.
What is the CVSS score of CVE-2025-47287?
CVE-2025-47287 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2025-47287?
CVE-2025-47287 is classified under CWE-770: Allocation of Resources Without Limits or Throttling (The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.).
How can I check PyPI dependencies for CVE-2025-47287?
Run the dependency tree command: 'pip show tornado'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-7cx3-6m66-7c5m",
  "modified" : "2025-05-29T06:31:17Z",
  "published" : "2025-05-16T14:12:40Z",
  "aliases" : [ "CVE-2025-47287" ],
  "summary" : "Tornado vulnerable to excessive logging caused by malformed multipart form data",
  "details" : "### Summary\n\nWhen Tornado's ``multipart/form-data`` parser encounters certain errors, it logs a warning but continues trying to parse the remainder of the data. This allows remote attackers to generate an extremely high volume of logs, constituting a DoS attack. This DoS is compounded by the fact that the logging subsystem is synchronous.\n\n### Affected versions\n\nAll versions of Tornado prior to 6.5 are affected. The vulnerable parser is enabled by default.\n\n### Solution\n\nUpgrade to Tornado version 6.5. In the meantime, risk can be mitigated by blocking `Content-Type: multipart/form-data` in a proxy.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "tornado"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "6.5"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/tornadoweb/tornado/security/advisories/GHSA-7cx3-6m66-7c5m"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-47287"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/tornadoweb/tornado/commit/b39b892bf78fe8fea01dd45199aa88307e7162f3"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/tornadoweb/tornado"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2025/05/msg00038.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-770" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-05-16T14:12:40Z",
    "nvd_published_at" : "2025-05-15T22:15:18Z"
  }
}