medium CVSS 5.5 EPSS 0.28%

CVE-2026-40610·Python vulnerability

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.

Severity
medium
Software
Python
Fixed in
1.4.39
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at 0.28% — higher than 20% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Affected versions

Until: 1.4.39

Fixed in: 1.4.39

How to fix this CVE

Update BentoML to version 1.4.39 or later to patch the symlink-following vulnerability in the build packaging workflow. If you are using BentoML for model serving, immediately audit any Bento artifacts built from untrusted sources or external repositories, as they may contain exfiltrated sensitive files such as credentials or SSH keys. Review your build environment logs to identify any suspicious symlink creation or file access patterns during recent build operations.

sudo dnf upgrade python3-bentoml

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check the installed BentoML version by running `pip show bentoml | grep Version`
  2. Step 2: Verify if the version is 1.4.38 or earlier; if so, the system is vulnerable
  3. Step 3: Search build logs for symlink creation events using `find /path/to/build/context -type l -ls` to identify any suspicious symbolic links
  4. Step 4: Confirm the fix by upgrading BentoML and re-running `pip show bentoml` to verify version 1.4.39 or later is installed

FAQ

What is CVE-2026-40610?

CVE-2026-40610 is a local file disclosure vulnerability in BentoML versions up to 1.4.38 where the build workflow unsafely dereferences symlinks within the build context, allowing attackers to inject symbolic links that cause sensitive local files (credentials, SSH keys, API tokens) to be packaged into Bento artifacts.

Is CVE-2026-40610 being actively exploited?

No, CVE-2026-40610 is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, and no public exploits are currently available. However, the attack requires only local access to the build context, making it a plausible threat in shared development environments.

What versions of BentoML are affected by CVE-2026-40610?

BentoML versions 1.4.38 and all prior versions are vulnerable. Version 1.4.39 and later include the fix.

How do I check if my server is vulnerable to CVE-2026-40610?

Run `pip show bentoml` and check the Version field. If the version is 1.4.38 or earlier, you are vulnerable. If version 1.4.39 or later is installed, you are patched.

Does Defensia detect CVE-2026-40610?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If BentoML is installed on a monitored server, CVE-2026-40610 will appear in your dashboard with remediation steps and affected version details.

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References

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