CVE-2020-6173: Tuf Denial of Service Vulnerability

MODERATE
Advisory Identifier: GHSA-2828-9vh6-9m6j
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CVSS 5.3
CWE-400
Published
Advisory Summary

CVE-2020-6173 is a MODERATE (CVSS 5.3) denial of service vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting Tuf libraries in the PyPI ecosystem. The issue involves client denial of service on tuf. Remediation is available by upgrading affected packages to version 0.12.2.

CVE-2020-6173 at a Glance

CVE Identifier CVE-2020-6173
GHSA Identifier GHSA-2828-9vh6-9m6j
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-400: Uncontrolled Resource Consumption
Affected Product Tuf
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 5.3

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:L).

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 Low (A:L)

How to Fix CVE-2020-6173

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

tuf fixed: 0.12.2 
pip install tuf>=0.12.2
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 tuf

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2020-6173, inspect your installed packages using pip:

pip show tuf

Analyze the terminal output to locate any version of Tuf in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.12.2), your application is affected.

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

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-400: Uncontrolled Resource Consumption, where the product does not properly control the allocation and maintenance of a limited resource. In Tuf, 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

### Impact An attacker who can gain file access to the repository and modify metadata files may cause a denial of service to clients by creating many invalid signatures on a metadata file. Having a large number of signatures to verify will delay the moment when the client will determine the signature is not valid. This delay may be for at least a few minutes, but possibly could be longer especially if multiple files are impacted. The tuf maintainers would like to thank Erik MacLean of Analog Devices, Inc. for reporting this issue. ### Patches No fix exists for this issue. ### Workarounds No workarounds are known for this issue. ### References * [CVE-2020-6173](https://nvd.nist.gov/vuln/detail/CVE-2020-6173) * [Issue #973](https://github.com/theupdateframework/tuf/issues/973)

CVE-2020-6173 Affected Tuf Versions

1 component(s)
Fixed Versions:
0.12.2
Product / Package Ecosystem Affected Versions Fixed Version
tuf
pypi/tuf
PyPI
≥ 0.7.2
< 0.12.2
0.12.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/theupdateframework/tuf/security/advisories/GHSA-2828-9vh6-9m6j
NVD — CVE-2020-6173 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-6173
Tuf Source Repository REPOSITORY
https://github.com/theupdateframework/tuf/issues/973
Tuf Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/tuf/PYSEC-2020-146.yaml
Tuf Source Repository REPOSITORY
https://github.com/theupdateframework/tuf
Tuf Source Repository REPOSITORY
https://github.com/theupdateframework/tuf/commits/develop

Frequently Asked Questions

What is CVE-2020-6173?
CVE-2020-6173 is a security vulnerability in Tuf involving Client Denial of Service on TUF under CWE-400: Uncontrolled Resource Consumption.
Which Tuf versions are affected?
Affected versions include releases prior to 0.12.2 across affected packages: tuf.
What version fixes CVE-2020-6173?
Upgrading to 0.12.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is tuf affected?
Yes, tuf is affected in releases prior to 0.12.2. Upgrade your dependency to 0.12.2 or later.
What is the CVSS score of CVE-2020-6173?
CVE-2020-6173 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
What CWE is associated with CVE-2020-6173?
CVE-2020-6173 is classified under CWE-400: Uncontrolled Resource Consumption (The product does not properly control the allocation and maintenance of a limited resource.).
How can I check PyPI dependencies for CVE-2020-6173?
Run the dependency tree command: 'pip show tuf'. 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-2828-9vh6-9m6j",
  "modified" : "2024-11-18T22:40:00Z",
  "published" : "2020-08-21T16:25:48Z",
  "aliases" : [ "CVE-2020-6173" ],
  "summary" : "Client Denial of Service on TUF",
  "details" : "### Impact\nAn attacker who can gain file access to the repository and modify metadata files may cause a denial of service to clients by creating many invalid signatures on a metadata file. Having a large number of signatures to verify will delay the moment when the client will determine the signature is not valid. This delay may be for at least a few minutes, but possibly could be longer especially if multiple files are impacted.\n\nThe tuf maintainers would like to thank Erik MacLean of Analog Devices, Inc. for reporting this issue.\n\n### Patches\nNo fix exists for this issue. \n\n### Workarounds\nNo workarounds are known for this issue.\n\n### References\n* [CVE-2020-6173](https://nvd.nist.gov/vuln/detail/CVE-2020-6173)\n* [Issue #973](https://github.com/theupdateframework/tuf/issues/973)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "tuf"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.7.2"
      }, {
        "fixed" : "0.12.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/theupdateframework/tuf/security/advisories/GHSA-2828-9vh6-9m6j"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-6173"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/theupdateframework/tuf/issues/973"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/tuf/PYSEC-2020-146.yaml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/theupdateframework/tuf"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/theupdateframework/tuf/commits/develop"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-400" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-08-21T16:19:09Z",
    "nvd_published_at" : null
  }
}