PYSEC-2026-4179

Vulnerability from pysec - Published: 2026-10-01 16:38 - Updated: 2026-10-01 17:10
VLAI
Details

Summary

The audio decode-duration guard (max_duration_s, env VLLM_MAX_AUDIO_DECODE_DURATION_S, default 600s) that protects against audio decompression-bomb DoS is wired into only the speech-to-text path (/v1/audio/transcriptions). The chat audio path (/v1/chat/completions, input_audio content parts) calls the same decoder with no limit, so an unauthenticated client can submit a few-KB compressed audio file that expands to multiple GB of float32 PCM at decode time, OOM-killing the worker. This is a distinct sibling of CVE-2026-5497 (video frame-count bomb, VideoMediaIO.load_base64) and GHSA-pq5c-rjhq-qp7p (image) in the same media subsystem.

Verified against main at HEAD d78650c (2026-06-16); applicable to the latest release v0.23.0.

Details

The guard rejects long audio during decode (before allocation), implemented in vllm/multimodal/media/audio.py: - load_audio_pyav — metadata reject (~82-98) and live sample-count reject (~129-136) - load_audio_soundfile — frames reject (~165-174)

All are gated on if max_duration_s is not None.

It is passed in exactly one place — the transcription serving layer:

# .../speech_to_text/base/serving.py:~170-174
load_audio(buf, sr=..., max_duration_s=self.max_audio_decode_duration_s)
#   self.max_audio_decode_duration_s = envs.VLLM_MAX_AUDIO_DECODE_DURATION_S  (default 600)

The chat path never threads it:

# vllm/multimodal/media/audio.py:237-238
def load_bytes(self, data: bytes) -> tuple[npt.NDArray, float]:
    return load_audio(BytesIO(data), sr=None)   # no max_duration_s -> every guard above is skipped

Unauthenticated reachability chain (chat): parse_input_audio (chat_utils.py) -> parse_audio -> connector.fetch_audio -> AudioMediaIO._load_data_url -> load_base64 -> load_bytes -> load_audio(..., sr=None). The connector never passes max_duration_s, and inline data: URLs need no HTTP fetch (so VLLM_AUDIO_FETCH_TIMEOUT does not bound them). The OpenAI-compatible server has no auth by default (auth only when --api-key / VLLM_API_KEY is set).

Impact

Unauthenticated remote denial of service (availability) via memory amplification on a default-no-auth endpoint, on any deployment serving an audio-capable model. Same class and impact as the sibling CVE-2026-5497 (video). CWE-770 / CWE-409.

Fix

A fix was introduced in this MR: https://github.com/vllm-project/vllm/pull/45908

Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Impacted products
Name purl
vllm pkg:pypi/vllm
Aliases
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "vllm",
        "purl": "pkg:pypi/vllm"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.24.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.0.1",
        "0.1.0",
        "0.1.1",
        "0.1.2",
        "0.1.3",
        "0.1.4",
        "0.1.5",
        "0.1.6",
        "0.1.7",
        "0.10.0",
        "0.10.1",
        "0.10.1.1",
        "0.10.2",
        "0.11.0",
        "0.11.1",
        "0.11.2",
        "0.12.0",
        "0.13.0",
        "0.14.0",
        "0.14.1",
        "0.15.0",
        "0.15.1",
        "0.16.0",
        "0.17.0",
        "0.17.1",
        "0.18.0",
        "0.18.1",
        "0.19.0",
        "0.19.1",
        "0.2.0",
        "0.2.1",
        "0.2.1.post1",
        "0.2.2",
        "0.2.3",
        "0.2.4",
        "0.2.5",
        "0.2.6",
        "0.2.7",
        "0.20.0",
        "0.20.1",
        "0.20.2",
        "0.21.0",
        "0.22.0",
        "0.22.1",
        "0.23.0",
        "0.3.0",
        "0.3.1",
        "0.3.2",
        "0.3.3",
        "0.4.0",
        "0.4.0.post1",
        "0.4.1",
        "0.4.2",
        "0.4.3",
        "0.5.0",
        "0.5.0.post1",
        "0.5.1",
        "0.5.2",
        "0.5.3",
        "0.5.3.post1",
        "0.5.4",
        "0.5.5",
        "0.6.0",
        "0.6.1",
        "0.6.1.post1",
        "0.6.1.post2",
        "0.6.2",
        "0.6.3",
        "0.6.3.post1",
        "0.6.4",
        "0.6.4.post1",
        "0.6.5",
        "0.6.6",
        "0.6.6.post1",
        "0.7.0",
        "0.7.1",
        "0.7.2",
        "0.7.3",
        "0.8.0",
        "0.8.1",
        "0.8.2",
        "0.8.3",
        "0.8.4",
        "0.8.5",
        "0.8.5.post1",
        "0.9.0",
        "0.9.0.1",
        "0.9.1",
        "0.9.2"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-57173",
    "GHSA-hcwq-8wjf-3gcr"
  ],
  "details": "### Summary\nThe audio decode-duration guard (`max_duration_s`, env `VLLM_MAX_AUDIO_DECODE_DURATION_S`, default 600s) that protects against audio decompression-bomb DoS is wired into **only** the speech-to-text path (`/v1/audio/transcriptions`). The **chat** audio path (`/v1/chat/completions`, `input_audio` content parts) calls the same decoder with **no** limit, so an **unauthenticated** client can submit a few-KB compressed audio file that expands to multiple GB of float32 PCM at decode time, OOM-killing the worker. This is a distinct sibling of **CVE-2026-5497** (video frame-count bomb, `VideoMediaIO.load_base64`) and **GHSA-pq5c-rjhq-qp7p** (image) in the same media subsystem.\n\nVerified against `main` at HEAD `d78650c` (2026-06-16); applicable to the latest release v0.23.0.\n\n### Details\nThe guard rejects long audio *during* decode (before allocation), implemented in `vllm/multimodal/media/audio.py`:\n- `load_audio_pyav` \u2014 metadata reject (~82-98) and live sample-count reject (~129-136)\n- `load_audio_soundfile` \u2014 frames reject (~165-174)\n\nAll are gated on `if max_duration_s is not None`.\n\nIt is passed in exactly **one** place \u2014 the transcription serving layer:\n```python\n# .../speech_to_text/base/serving.py:~170-174\nload_audio(buf, sr=..., max_duration_s=self.max_audio_decode_duration_s)\n#   self.max_audio_decode_duration_s = envs.VLLM_MAX_AUDIO_DECODE_DURATION_S  (default 600)\n```\n\nThe chat path never threads it:\n```python\n# vllm/multimodal/media/audio.py:237-238\ndef load_bytes(self, data: bytes) -\u003e tuple[npt.NDArray, float]:\n    return load_audio(BytesIO(data), sr=None)   # no max_duration_s -\u003e every guard above is skipped\n```\n\nUnauthenticated reachability chain (chat):\n`parse_input_audio` (`chat_utils.py`) -\u003e `parse_audio` -\u003e `connector.fetch_audio` -\u003e `AudioMediaIO._load_data_url` -\u003e `load_base64` -\u003e `load_bytes` -\u003e `load_audio(..., sr=None)`. The connector never passes `max_duration_s`, and inline `data:` URLs need no HTTP fetch (so `VLLM_AUDIO_FETCH_TIMEOUT` does not bound them). The OpenAI-compatible server has no auth by default (auth only when `--api-key` / `VLLM_API_KEY` is set).\n\n### Impact\nUnauthenticated remote denial of service (availability) via memory amplification on a default-no-auth endpoint, on any deployment serving an audio-capable model. Same class and impact as the sibling CVE-2026-5497 (video). CWE-770 / CWE-409.\n\n### Fix\nA fix was introduced in this MR: https://github.com/vllm-project/vllm/pull/45908",
  "id": "PYSEC-2026-4179",
  "modified": "2026-10-01T17:10:45.836187Z",
  "published": "2026-10-01T16:38:32.289483Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/vllm-project/vllm/security/advisories/GHSA-hcwq-8wjf-3gcr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-57173"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vllm-project/vllm/pull/45908"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vllm-project/vllm/commit/3d20275bb4d434f53055c3c0b645fd8bb072965e"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/vllm-project/vllm"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vllm-project/vllm/releases/tag/v0.24.0"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/vllm"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-hcwq-8wjf-3gcr"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "vLLM: Unauthenticated audio decompression-bomb DoS in /v1/chat/completions"
}



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