BentoML up to 1.4.35 Bento safe_extract_tarfile link following

Summaryinfo

A vulnerability identified as critical has been detected in BentoML up to 1.4.35. Affected by this vulnerability is the function safe_extract_tarfile of the component Bento Handler. The manipulation leads to link following. This vulnerability is listed as CVE-2026-27905. The attack must be carried out locally. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in BentoML up to 1.4.35. It has been rated as critical. This issue affects the function safe_extract_tarfile of the component Bento Handler. The manipulation with an unknown input leads to a link following vulnerability. Using CWE to declare the problem leads to CWE-59. The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

BentoML is a Python library for building online serving systems optimized for AI apps and model inference. Prior to 1.4.36, the safe_extract_tarfile() function validates that each tar member's path is within the destination directory, but for symlink members it only validates the symlink's own path, not the symlink's target. An attacker can create a malicious bento/model tar file containing a symlink pointing outside the extraction directory, followed by a regular file that writes through the symlink, achieving arbitrary file write on the host filesystem. This vulnerability is fixed in 1.4.36.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-27905 since 02/24/2026. The exploitation is known to be easy. Attacking locally is a requirement. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 300821 (BentoML < 1.4.36 Arbitrary File Write), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 1.4.36 eliminates this vulnerability. Applying the patch 4e0eb007765ac04c7924220d643f264715cc9670 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (300821). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Name

• BentoML

Version

• 1.4.0
• 1.4.1
• 1.4.2
• 1.4.3
• 1.4.4
• 1.4.5
• 1.4.6
• 1.4.7
• 1.4.8
• 1.4.9
• 1.4.10
• 1.4.11
• 1.4.12
• 1.4.13
• 1.4.14
• 1.4.15
• 1.4.16
• 1.4.17
• 1.4.18
• 1.4.19
• 1.4.20
• 1.4.21
• 1.4.22
• 1.4.23
• 1.4.24
• 1.4.25
• 1.4.26
• 1.4.27
• 1.4.28
• 1.4.29
• 1.4.30
• 1.4.31
• 1.4.32
• 1.4.33
• 1.4.34
• 1.4.35

License

• open-source

Website

• Product: https://github.com/bentoml/BentoML/

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

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