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Improper verification of signature threshold in tough

High severity GitHub Reviewed Published Jul 9, 2020 in awslabs/tough • Updated Feb 3, 2023

Package

cargo tough (Rust)

Affected versions

< 0.7.1

Patched versions

0.7.1

Description

Impact

The tough library, prior to 0.7.1, does not properly verify the uniqueness of keys in the signatures provided to meet the threshold of cryptographic signatures. It allows someone with access to a valid signing key to create multiple valid signatures in order to circumvent TUF requiring a minimum threshold of unique keys before the metadata is considered valid.

AWS would like to thank Erick Tryzelaar of the Google Fuchsia Team for reporting this issue.

Patches

A fix is available in version 0.7.1.

Workarounds

No workarounds to this issue are known.

References

CVE-2020-6174 is assigned to the same issue in the TUF reference implementation.

theupdateframework/python-tuf#974
https://nvd.nist.gov/vuln/detail/CVE-2020-6174

For more information

If you have any questions or comments about this advisory, contact AWS Security at aws-security@amazon.com.

References

@iliana iliana published to awslabs/tough Jul 9, 2020
Published by the National Vulnerability Database Jul 9, 2020
Reviewed Aug 18, 2021
Published to the GitHub Advisory Database Aug 25, 2021
Last updated Feb 3, 2023

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

EPSS score

0.124%
(48th percentile)

Weaknesses

CVE ID

CVE-2020-15093

GHSA ID

GHSA-5q2r-92f9-4m49

Source code

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