CVE-2021-41131 Information

Description

python-tuf is a Python reference implementation of The Update Framework (TUF). In both clients (tuf/client and tuf/ngclient) there is a path traversal vulnerability that in the worst case can overwrite files ending in .json anywhere on the client system on a call to get_one_valid_targetinfo(). It occurs because the rolename is used to form the filename and may contain path traversal characters (ie ../../name.json). The impact is mitigated by a few facts: It only affects implementations that allow arbitrary rolename selection for delegated targets metadata The attack requires the ability to A) insert new metadata for the path-traversing role and B) get the role delegated by an existing targets metadata The written file content is heavily restricted since it needs to be a valid signed targets file. The file extension is always .json. A fix is available in version 0.19 or newer. There are no workarounds that do not require code changes. Clients can restrict the allowed character set for rolenames or they can store metadata in files named in a way that is not vulnerable: neither of these approaches is possible without modifying python-tuf.

CVSS Vector

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

Reference

https://github.com/theupdateframework/python-tuf/commit/4ad7ae48fda594b640139c3b7eae21ed5155a102 https://github.com/theupdateframework/python-tuf/security/advisories/GHSA-wjw6-2cqr-j4qr https://github.com/theupdateframework/python-tuf/issues/1527

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction Required

NONE

Scope

NONE

Confidentiality Impact

CHANGED

Integrity Impact

NONE

Availability Impact

HIGH

Base Score

HIGH

Base Severity

8.7