CVE-2026-27905 BentoML has an Arbitrary File Write via Symlink Path Traversal in Tar Extraction
Attackers can achieve arbitrary file write on the host by exploiting symlink validation flaws in tar extraction, potentially leading to code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-27905?
CVE-2026-27905 is a high-severity path traversal vulnerability in BentoML, published on 3 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-59
Which versions are affected by CVE-2026-27905?
3 open source packages ship an affected version, including bentoml. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
bentoml PyPI | All versions | 1.4.36 |
bentoml PyPI | All versions | 1.4.36 |
bentoml PyPI | All versions | 1.4.36 |
Products include Bentoml Bentoml.
How do I fix CVE-2026-27905?
Upgrade bentoml to 1.4.36 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-27905 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-27905 exists.
Other vulnerabilities in BentoML
- CVE-2025-54381 BentoML is Vulnerable to an SSRF Attack Through File Upload Processing
- CVE-2025-32375 Insecure Deserialization leads to RCE in BentoML's runner server
- CVE-2025-27520 BentoML Allows Remote Code Execution (RCE) via Insecure Deserialization
- CVE-2026-44345 BentoML: Dockerfile command injection via docker.base_image
- CVE-2026-44346 BentoML: Dockerfile command injection via envs[*].name in bentofile.yaml
Sources
Also known as GHSA-m6w7-qv66-g3mf, PYSEC-2026-2398.