MosaicML Composer up to 0.32.1 Checkpoint Extraction checkpoint.py tarball.extractall path traversal

Summaryinfo

A vulnerability identified as critical has been detected in MosaicML Composer up to 0.32.1. This impacts the function tarball.extractall of the file composer/utils/checkpoint.py of the component Checkpoint Extraction. This manipulation causes path traversal. This vulnerability is tracked as CVE-2026-109153. The attack is possible to be carried out remotely. No exploit exists. The vendor was contacted early about this disclosure.

Detailsinfo

A vulnerability was found in MosaicML Composer up to 0.32.1. It has been declared as critical. Affected by this vulnerability is the function tarball.extractall of the file composer/utils/checkpoint.py of the component Checkpoint Extraction. The manipulation with an unknown input leads to a path traversal vulnerability. The CWE definition for the vulnerability is CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. As an impact it is known to affect confidentiality, integrity, and availability.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-109153. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/12/2026). The attack technique deployed by this issue is T1006 according to MITRE ATT&CK.

The vendor was contacted early about this disclosure.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

• MosaicML

Name

• Composer

Version

• 0.32.0
• 0.32.1

Website

• Product: https://github.com/mosaicml/composer/

CPE 2.3info

• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Submitinfo

Accepted

• Submit #978647: mosaicml composer 0.32.1 Path Traversal (by github.com)

Be aware that VulDB is the high quality source for vulnerability data.

Discussion