CVE-2026-40610 BentoML has Information Disclosure in `bentoml build` via symlink traversal in the build context

What is CVE-2026-40610?

CVE-2026-40610 is a medium-severity path traversal vulnerability in BentoML, published on 22 May 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

Official description

BentoML is a Python library for building online serving systems optimized for AI apps and model inference. In versions 1.4.38 and prior, the build packaging workflow follows attacker-controlled symlinks inside the build context and copies the referenced file contents into the generated Bento artifact. If a victim builds an untrusted repository or other attacker-supplied build context, the attacker can place a symlink such as loot.txt -> /tmp/outside-marker.txt or a link to a more sensitive local file. When bentoml build runs, BentoML dereferences the symlink and packages the target file contents into the Bento. The leaked file can then propagate further through export, push, or containerization workflows. An attacker can exfiltrate local files from the build host into the Bento artifact, exposing secrets such as cloud credentials, SSH keys, API tokens, environment files, or other sensitive local configurations. Because Bento artifacts are commonly exported, uploaded, stored, or containerized after build, the leaked file contents can spread beyond the original build machine. This issue has been fixed in version 1.4.39.

Weakness: CWE-59

Which versions are affected by CVE-2026-40610?

3 open source packages ship an affected version, including bentoml. It affects 1 product.

Products include Bentoml Bentoml.

How do I fix CVE-2026-40610?

Upgrade bentoml to 1.4.39 or later.

Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.

Is CVE-2026-40610 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40610 exists.

Other vulnerabilities in BentoML

• CVE-2025-54381 BentoML is Vulnerable to an SSRF Attack Through File Upload Processing Critical 9.9
• CVE-2025-32375 Insecure Deserialization leads to RCE in BentoML's runner server Critical 9.8
• CVE-2025-27520 BentoML Allows Remote Code Execution (RCE) via Insecure Deserialization Critical 9.8
• CVE-2026-44345 BentoML: Dockerfile command injection via docker.base_image High 8.8
• CVE-2026-44346 BentoML: Dockerfile command injection via envs[*].name in bentofile.yaml High 8.8

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-mcfx-4vc6-qgxv, PYSEC-2026-2399.