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.
Published 2021-10-19 18:15:08
Updated 2021-10-22 20:44:12
Source GitHub, Inc.
View at NVD,   CVE.org
Vulnerability category: Directory traversal

Exploit prediction scoring system (EPSS) score for CVE-2021-41131

0.14%
Probability of exploitation activity in the next 30 days EPSS Score History
~ 50 %
Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2021-41131

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
8.8
HIGH AV:N/AC:M/Au:N/C:N/I:C/A:C
8.6
9.2
NIST
8.7
HIGH CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:H
2.2
5.8
NIST
7.5
HIGH CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N
2.2
4.7
GitHub, Inc.

CWE ids for CVE-2021-41131

  • The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
    Assigned by: security-advisories@github.com (Primary)

References for CVE-2021-41131

Products affected by CVE-2021-41131

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