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Incorrect threshold signature computation

High
joshuagl published GHSA-pwqf-9h7j-7mv8 Aug 20, 2020

Package

tuf (pypi)

Affected versions

< 0.12.2

Patched versions

0.12.2

Description

Impact

Metadadata signature verification, as used in tuf.client.updater, counted each of multiple signatures with identical authorized keyids separately towards the threshold. Therefore, an attacker with access to a valid signing key could create multiple valid signatures in order to meet the minimum threshold of keys before the metadata was considered valid.

The tuf maintainers would like to thank Erik MacLean of Analog Devices, Inc. for reporting this issue.

Patches

A fix is available in version 0.12.2 or newer.

Workarounds

No workarounds are known for this issue.

References

Severity

High

CVE ID

CVE-2020-6174

Weaknesses

No CWEs