---
id: CVE-2026-29790
aliases:
  - GHSA-w75w-9qv4-j5xj
  - PYSEC-2026-2440
title: dbt-common's commonprefix() doesn't protect against path traversal
summary: dbt-common's commonprefix() doesn't protect against path traversal
severity: low
vendor: dbt-common
product: dbt-common
ecosystem: pip
affected:
  - dbt-common < 1.34.2
  - 'dbt-common >= 1.35.0, < 1.37.3'
patched:
  - dbt-common 1.34.2
  - dbt-common 1.37.3
published: '2026-03-05'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:50:41.434044516Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-w75w-9qv4-j5xj'
references:
  - url: >-
      https://github.com/dbt-labs/dbt-common/security/advisories/GHSA-w75w-9qv4-j5xj
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-29790'
  - url: 'https://github.com/pypa/pip/pull/13777'
  - url: >-
      https://github.com/dbt-labs/dbt-common/commit/e547954a48bac9394ef6eb98432e429dce9a7709
  - url: 'https://docs.python.org/3/library/os.path.html#os.path.commonpath'
  - url: 'https://github.com/advisories/GHSA-6vgw-5pg2-w6jp'
  - url: 'https://github.com/dbt-labs/dbt-common'
tags:
  - osv
  - pip
epss: 0.00379
epssPercentile: 0.29031
ingestedAt: '2026-07-13T18:58:04.157Z'
---

## Overview

### Impact
_What kind of vulnerability is it? Who is impacted?_

A path traversal vulnerability exists in dbt-common's `safe_extract()` 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

## Affected packages

- `dbt-common < 1.34.2`
- `dbt-common >= 1.35.0, < 1.37.3`

## Remediation

Upgrade to a patched release:

- `dbt-common 1.34.2`
- `dbt-common 1.37.3`