Is CVE-2026-78684 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-78684 being exploited in the wild.

How severe is CVE-2026-78684?

Medium severity, with a CVSS score of 5.3, published 25 August 2026.

Which products and versions are affected?

vllm (PyPI) ECOSYSTEM:introduced=0,fixed=0.27.0; Vllm before 0.27.0.

Is there a fix for CVE-2026-78684?

Yes. vllm (PyPI): upgrade to 0.27.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-78684 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-78684?

Check whether you run vllm (PyPI) or Vllm at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-78684: vLLM DeepStream backend classification and pixel-limit enforcement bypass

CVE-2026-78684 · Severity: medium · CVSS 5.3 · Published 2026-08-25

vLLM is an open-source inference engine for large language models that supports video input processing. Attackers can exploit a flaw in how the DeepStream GPU video decoder is classified to bypass resource controls and trigger a partial denial of service affecting concurrent requests. By requesting GPU-accelerated video decoding that was not pre-configured at startup, an unauthenticated attacker can cause legitimate requests to time out and fail.

Technologies: vllm (PyPI), Vllm. Vendors: PyPI, Vllm.

Quick answers

Is CVE-2026-78684 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-78684 being exploited in the wild.
How severe is CVE-2026-78684?: Medium severity, with a CVSS score of 5.3, published 25 August 2026.
Which products and versions are affected?: vllm (PyPI) ECOSYSTEM:introduced=0,fixed=0.27.0; Vllm before 0.27.0.
Is there a fix for CVE-2026-78684?: Yes. vllm (PyPI): upgrade to 0.27.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-78684 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-78684?: Check whether you run vllm (PyPI) or Vllm at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

vllm (PyPI): upgrade to 0.27.0 or later
```
pip install "vllm>=0.27.0"
```

Technical details

The vulnerability stems from three root causes: (1) DeepStream is registered as an inner codec of OpenCV rather than as a standalone GPU backend, allowing backend_requires_gpu() to return False and requests to bypass GPU backend validation in VideoMediaIO.merge_kwargs(); (2) the DeepStream decode path calls probe_metadata() but omits the _check_frame_pixel_limit() validation check applied by other backends (OpenCV, PyAV, TorchCodec, PyNvVideoCodec), allowing oversized frames to be processed; and (3) DeepStream uses a process-wide singleton decode pool initialized on first request with user-controlled pool size, rather than at startup. An unauthenticated client can send a video inference request specifying backend="deepstream" to initialize the GPU decode pool and submit video that would be rejected by other backends, exhausting GPU resources and causing timeouts for concurrent requests. The fix requires registering DeepStream as a GPU-classified codec, enforcing pixel-limit checks, and making pool initialization startup-only.

Affected products

vLLM vLLM before 0.27.0

Identifiers

CVE-2026-78684
PYSEC-2026-4003

Timeline

2026-08-25: disclosed
2026-08-11: patched: fix available in version 0.27.0 and later

References

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