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pnpm incorrectly parses tar archives relative to specification

High severity GitHub Reviewed Published Aug 1, 2023 in pnpm/pnpm • Updated Nov 11, 2023

Package

npm @pnpm/cafs (npm)

Affected versions

< 7.0.5

Patched versions

7.0.5
npm @pnpm/exe (npm)
< 7.33.4
>= 8.0.0, < 8.6.8
7.33.4
8.6.8
npm @pnpm/linux-arm64 (npm)
< 7.33.4
>= 8.0.0, < 8.6.8
7.33.4
8.6.8
npm @pnpm/linux-x64 (npm)
< 7.33.4
>= 8.0.0, < 8.6.8
7.33.4
8.6.8
npm @pnpm/linuxstatic-arm64 (npm)
< 7.33.4
>= 8.0.0, < 8.6.8
7.33.4
8.6.8
npm @pnpm/macos-arm64 (npm)
< 7.33.4
>= 8.0.0, < 8.6.8
7.33.4
8.6.8
npm @pnpm/macos-x64 (npm)
< 7.33.4
>= 8.0.0, < 8.6.8
7.33.4
8.6.8
npm @pnpm/win-x64 (npm)
< 7.33.4
>= 8.0.0, < 8.6.8
7.33.4
8.6.8
npm pnpm (npm)
< 7.33.4
>= 8.0.0, < 8.6.8
7.33.4
8.6.8

Description

Summary

It is possible to construct a tarball that, when installed via npm or parsed by the registry is safe, but when installed via pnpm is malicious, due to how pnpm parses tar archives.

Details

The TAR format is an append-only archive format, and as such, the specification for how to update a file is to add a new record to the end with the updated version of the file. This means that it is completely valid for an archive to contain multiple copies of, say, package.json, and the expected behavior when extracting is that all versions other than the last get ignored.

This is further complicated by that during tarball extraction, all package managers are configured to drop the first path component, so collisions can be created simply by using multiple root folders in the archive, even without performing updates.

When pnpm extracts a tar archive via tar-stream, it appears to extract only the first file of a given name and discards all subsequent files with the same name.

PoC

Create a root folder with the following layout:

  • a/package.json
  • package/package.json
  • z/package.json

File contents:

a/package.json

{
    "name": "test-package",
    "version": "0.1.0",
    "description": "This is a bad version of a test package",
    "dependencies": {
        "react": "^15"
    }
}

package/package.json

{
    "name": "test-package",
    "version": "0.1.0",
    "description": "This is a bad version of a test package",
    "dependencies": {
        "react": "^16"
    }
}

z/package.json

{
    "name": "test-package",
    "version": "0.1.0",
    "description": "This is the good version of a test package",
    "dependencies": {
        "react": "^17"
    }
}

Then use the tar binary to produce a tarball (working directory is the root folder):
tar -c -z --format ustar -f package.tgz a package z
The order of the folders at the end matters; whichever one is last will end up being the package.json that wins when extracted by npm; the one that is first will be the one that wins when extracted by pnpm.

Install the tarball via the file: protocol.

Observe that with npm, the lockfile has react@17, while with pnpm it has react@15.

Impact

This can result in a package that appears safe on the npm registry or when installed via npm being replaced with a compromised or malicious version when installed via pnpm.

References

@zkochan zkochan published to pnpm/pnpm Aug 1, 2023
Published by the National Vulnerability Database Aug 1, 2023
Published to the GitHub Advisory Database Aug 1, 2023
Reviewed Aug 1, 2023
Last updated Nov 11, 2023

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS score

0.166%
(54th percentile)

Weaknesses

CVE ID

CVE-2023-37478

GHSA ID

GHSA-5r98-f33j-g8h7

Source code

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