CVE-2021-38511 is a high-severity (CVSS 7.5) CWE-59 vulnerability in tar. 2 public exploit references exist, so weaponization risk is real. A fix is available for tar — see the affected versions and patch details below.
Links in archive can create arbitrary directories
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-38511 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
tarReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
When unpacking a tarball that contains a symlink the tar crate may create directories outside of the directory it's supposed to unpack into. The function errors when it's trying to create a file, but the folders are already created at this point.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | tar | all versions | 0.4.36cargo update -p tar --precise 0.4.36 |
Affected Products
tartar_projectResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tar, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update tar to 0.4.36 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-38511 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2021-38511 in your dependencies?
Find it across crates.io, including transitive dependencies.