CVE-2026-54233

vLLM's /v1/audio/transcriptions endpoint limits compressed upload size but not decoded PCM output. A 25MB OPUS file expands to ~14.9GB of float32 PCM at decode time. Tested on vLLM v0.19.0.

Details

SpeechToTextProcessor rejects uploads over VLLM_MAX_AUDIO_CLIP_FILESIZE_MB (default 25MB) based on compressed byte length, but the audio decoder in audio.py accumulates all decoded frames into memory with no size limit before returning:

# speech_to_text.py L184-189
if len(audio_data) / 1024 ** 2 > self.max_audio_filesize_mb:
    raise VLLMValidationError(...)
y, sr = load_audio(buf, sr=self.asr_config.sample_rate)  # decoded size unchecked

# audio.py L77-107
chunks: list[npt.NDArray] = []
for frame in container.decode(stream):
    chunks.append(frame.to_ndarray())
audio = np.concatenate(chunks, axis=-1).astype(np.float32)  # single contiguous allocation

A 25MB OPUS file at 6kbps encodes ~8.7 hours of audio. Decoding produces ~5.7GB of float32 PCM (232x amplification), and np.concatenate then allocates a second contiguous array, bringing peak RSS to ~14.9GB from a single request. SpeechToTextConfig.max_audio_clip_s (default 30s) applies only after the full decode and does not prevent the allocation.

An unauthenticated attacker can exhaust server memory with a small number of concurrent requests, each a valid upload within the documented size limit. Severity was assessed with reference to prior OOM vulnerability reports in vLLM.

CVE-2026-54233 has a CVSS score of 6.5 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.

Kodem intelligence

A fix for this vulnerability was merged here: https://github.com/vllm-project/vllm/pull/44970

1. What is CVE-2026-54233? CVE-2026-54233 is a medium-severity security vulnerability in vllm (pip), affecting versions <= 0.23.0. No fixed version is listed yet.
2. How severe is CVE-2026-54233? CVE-2026-54233 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of vllm are affected by CVE-2026-54233? vllm (pip) versions <= 0.23.0 is affected.
4. Is there a fix for CVE-2026-54233? No fixed version is listed for CVE-2026-54233 yet. Monitor the advisory for updates and apply mitigations in the interim.
5. Is CVE-2026-54233 exploitable, and should I be worried? Whether CVE-2026-54233 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-54233 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.