CVE-2021-37713

Workarounds

There is no reasonable way to work around this issue without performing the same path normalization procedures that node-tar now does.

Users are encouraged to upgrade to the latest patched versions of node-tar, rather than attempt to sanitize paths themselves.

Fix

The fixed versions strip path roots from all paths prior to being resolved against the extraction target folder, even if such paths are not "absolute".

Additionally, a path starting with a drive letter and then two dots, like c:../, would bypass the check for .. path portions. This is checked properly in the patched versions.

Finally, a defense in depth check is added, such that if the entry.absolute is outside of the extraction taret, and we are not in preservePaths:true mode, a warning is raised on that entry, and it is skipped. Currently, it is believed that this check is redundant, but it did catch some oversights in development.

Arbitrary File Creation, Arbitrary File Overwrite, Arbitrary Code Execution

node-tar aims to guarantee that any file whose location would be outside of the extraction target directory is not extracted. This is, in part, accomplished by sanitizing absolute paths of entries within the archive, skipping archive entries that contain .. path portions, and resolving the sanitized paths against the extraction target directory.

This logic was insufficient on Windows systems when extracting tar files that contained a path that was not an absolute path, but specified a drive letter different from the extraction target, such as C:some\path. If the drive letter does not match the extraction target, for example D:\extraction\dir, then the result of path.resolve(extractionDirectory, entryPath) would resolve against the current working directory on the C: drive, rather than the extraction target directory.

Additionally, a .. portion of the path could occur immediately after the drive letter, such as C:../foo, and was not properly sanitized by the logic that checked for .. within the normalized and split portions of the path.

This only affects users of node-tar on Windows systems.

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2021-37713 has a CVSS score of 8.2 (High). The vector is requires local access, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.4.18, 5.0.10, 6.1.9); upgrading removes the vulnerable code path.

Kodem intelligence

4.4.18 || 5.0.10 || 6.1.9

1. What is CVE-2021-37713? CVE-2021-37713 is a high-severity path traversal vulnerability in tar (npm), affecting versions < 4.4.18. It is fixed in 4.4.18, 5.0.10, 6.1.9. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2021-37713? CVE-2021-37713 has a CVSS score of 8.2 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of tar are affected by CVE-2021-37713? tar (npm) versions < 4.4.18 is affected.
4. Is there a fix for CVE-2021-37713? Yes. CVE-2021-37713 is fixed in 4.4.18, 5.0.10, 6.1.9. Upgrade to this version or later.
5. Is CVE-2021-37713 exploitable, and should I be worried? Whether CVE-2021-37713 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2021-37713 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2021-37713?
   • Upgrade tar to 4.4.18 or later
   • Upgrade tar to 5.0.10 or later
   • Upgrade tar to 6.1.9 or later