How severe is CVE-2021-41131?

CVE-2021-41131 has a CVSS score of 8.7/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-41131?

CVE-2021-41131 affects the following packages: tuf (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2021-41131?

Update tuf to 0.19.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-41131 is resolved across your whole dependency graph.

How do I detect CVE-2021-41131 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tuf, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-41131 if there is no patch (or I can't update yet)?

Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Is CVE-2021-41131 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-41131 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-41131?

CVE-2021-41131 has an EPSS (Exploit Prediction Scoring System) score of 1.5%, placing it in the 73th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-41131?

CVE-2021-41131 is classified as Path Traversal (CWE-22). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2021-41131 published, and has it been updated?

CVE-2021-41131 was published on October 19, 2021 and was last updated on August 27, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

HIGH severity

CVE-2021-41131 — tuf

HIGHFix: theupdateframework/python-tuf@4ad7ae4

CVE-2021-41131 is a high-severity (CVSS 8.7) Path Traversal vulnerability in tuf. A fix is available for tuf — see the affected versions and patch details below.

Client metadata path-traversal

Also known asGHSA-wjw6-2cqr-j4qrPYSEC-2021-376

Published

Oct 19, 2021

Updated

Aug 27, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs73th percentile — riskier than 73% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-41131 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 384,993 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

🐍tuf

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Impact

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.

Patches

A fix is available in version 0.19 or newer.

Workarounds

None 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.

References

For more information

If you have any questions or comments about this advisory:

Open an issue in python-tuf
Contact the maintainers by email or Slack

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`tuf`	all versions	0.19.0`pip install --upgrade 'tuf==0.19.0'`

Affected Products

1 product · 1 configurations

Application

the update frameworklinuxfoundation

≤ 0.18.1

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tuf, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update tuf to 0.19.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-41131 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Frequently Asked Questions

### Impact 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 an