CVE-2026-29790: dbt-common: commonprefix() doesn't protect against path traversal
Impact What kind of vulnerability is it? Who is impacted?
A path traversal vulnerability exists in dbt-common's safeextract() function used when extracting tarball archives. The function uses os.path.commonprefix() to validate that extracted files remain within the intended destination directory. However, commonprefix() compares paths character-by-character rather than by path components, allowing a malicious tarball to write files to sibling directories with matching name prefixes.
For example, when extracting to /tmp/packages, a crafted tarball could write files to /tmp/packagesevil/ by exploiting the character-based prefix matching.
This vulnerability affects users who: - Install dbt packages from untrusted sources - Process tarball archives through dbt-common's extraction utilities
The practical risk is limited because: - Exploitation requires a malicious tarball to be processed - File writes are restricted to sibling directories with matching prefixes (not arbitrary paths) - Packages from trusted sources (dbt Hub) are not affected
This is similar to CVE-2026-1703 in pip, which had a CVSS score of 3.9 (Low).
Patches Has the problem been patched? What versions should users upgrade to?
Fixed in dbt-common version 1.37.3 & 1.34.2, and patched for dbt-core 1.11.7 and 1.10.20 releases.
The fix replaces os.path.commonprefix() with os.path.commonpath(), which correctly compares paths by their components rather than characters.
Workarounds Is there a way for users to fix or remediate the vulnerability without upgrading?
- Only install dbt packages from trusted sources (official dbt Hub, verified git repositories) - Avoid installing packages from untrusted URLs or unverified third parties - Review package contents before installation when sourcing from external locations
Resources Are there any links users can visit to find out more?
1. CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'): https://cwe.mitre.org/data/definitions/22.html 2. CVE-2026-1703 (similar vulnerability in pip): https://nvd.nist.gov/vuln/detail/CVE-2026-1703 3. pip fix PR #13777: https://github.com/pypa/pip/pull/13777 4. Python documentation on commonpath vs commonprefix: https://docs.python.org/3/library/os.path.html#os.path.commonpath
Other sources
dbt-common is the shared common utilities for dbt-core and adapter implementations use. Prior to versions 1.34.2 and 1.37.3, a path traversal vulnerability exists in dbt-common's safeextract() function used when extracting tarball archives. The function uses os.path.commonprefix() to validate that extracted files remain within the intended destination directory. However, commonprefix() compares paths character-by-character rather than by path components, allowing a malicious tarball to write files to sibling directories with matching name prefixes. This issue has been patched in versions 1.34.2 and 1.37.3.
— MITRE
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2026-29790?
CVE-2026-29790 is classified as a path traversal vulnerability that can lead to unauthorized file access.
How do I fix CVE-2026-29790?
To mitigate CVE-2026-29790, upgrade the dbt-common package to version 1.37.3 or higher, or to version 1.34.2 if using an earlier version.
Who is impacted by CVE-2026-29790?
Users of dbt-common versions between 1.35.0 and 1.37.3, as well as versions below 1.34.2, are impacted by CVE-2026-29790.
What is the primary function affected by CVE-2026-29790?
The primary function affected by CVE-2026-29790 is `safe_extract()` within the dbt-common library.
What measures can be taken to prevent exploitation of CVE-2026-29790?
To prevent exploitation, ensure that your application does not accept untrusted input for file paths and limit user-accessible directories.