CVE-2026-27905: PYSEC-2026-2398 - BentoML Vulnerable to Arbitrary File Write via Symlink Path Traversal in Tar Extraction

CVE-2026-27905 · Severity: high · CVSS 7.8 · Published 2026-03-03

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.

Technologies: Bentoml, bentoml (PyPI). Vendors: BentoML, PyPI.

Quick answers

Is CVE-2026-27905 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-27905 being exploited in the wild.
How severe is CVE-2026-27905?
High severity, with a CVSS score of 7.8, published 3 March 2026.
Which products and versions are affected?
bentoml (PyPI) ECOSYSTEM:introduced=0,fixed=1.4.36.
Is there a fix for CVE-2026-27905?
Yes. bentoml (PyPI): upgrade to 1.4.36 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-27905?
Check whether you run Bentoml or bentoml (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • bentoml (PyPI): upgrade to 1.4.36 or later
    pip install "bentoml>=1.4.36"

Affected products

  • Bentoml
  • bentoml (PyPI) ECOSYSTEM:introduced=0,fixed=1.4.36

Identifiers

  • CVE-2026-27905
  • GHSA-m6w7-qv66-g3mf
  • PYSEC-2026-2398

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