BentoML has Information Disclosure in bentoml build via symlink traversal in the build context

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.5 · CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

EPSS

• CVE-2026-40610: 0.28% estimated exploitation activity in the next 30 days; percentile 21.00 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary BentoML's bentoml 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. Details The vulnerable code walks files under the build context and copies each matched entry into the Bento source directory: There is no validation that the resolved path of srcfile remains inside ctxpath before shutil.copy dereferences the source path. As a result, a repository-controlled symlink can cross the trust boundary from attacker-controlled repository content to developer/CI host…

Published by the source

7 May 2026, 16:39 UTC

Last modified by the source

13 Jul 2026, 16:42 UTC

Source last checked

26 Oct 2026, 13:45 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-mcfx-4vc6-qgxv

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-mcfx-4vc6-qgxv

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# Patch Next advisory brief: CVE-2026-40610

Advisory: BentoML has Information Disclosure in `bentoml build` via symlink traversal in the build context
IDs: CVE-2026-40610, GHSA-mcfx-4vc6-qgxv
Record: https://patchnext.com/advisories/cve-2026-40610 (revision 2, source checked 26 Oct 2026, 13:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: bentoml 1.4.39. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI bentoml: affected <= 1.4.38; fixed in 1.4.39

## Suggested inspection (read-only)
- `python -m pip show bentoml`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on bentoml.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-mcfx-4vc6-qgxv (OSV record GHSA-mcfx-4vc6-qgxv lists affected ranges: PyPI bentoml >=0 <1.4.39 (fixed))
- Verified: https://github.com/advisories/GHSA-mcfx-4vc6-qgxv (GitHub-reviewed advisory GHSA-mcfx-4vc6-qgxv lists affected ranges: PyPI bentoml >=0 <=1.4.38)

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