GHSA-grg2-63fw-f2qr
MEDIUMvLLM is vulnerable to DoS in Idefics3 vision models via image payload with ambiguous dimensions
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
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Description
Summary
Users can crash the vLLM engine serving multimodal models that use the Idefics3 vision model implementation by sending a specially crafted 1x1 pixel image. This causes a tensor dimension mismatch that results in an unhandled runtime error, leading to complete server termination.
Details
The vulnerability is triggered when the image processor encounters a 1x1 pixel image with shape (1, 1, 3) in HWC (Height, Width, Channel) format. Due to the ambiguous dimensions, the processor incorrectly assumes the image is in CHW (Channel, Height, Width) format with shape (3, H, W). This misinterpretation causes an incorrect calculation of the number of image patches, resulting in a fatal tensor split operation failure.
Crash location: vllm/model_executor/models/idefics3.py line 672:
def _process_image_input(self, image_input: ImageInputs) -> torch.Tensor | list[torch.Tensor]:
# ...
num_patches = image_input["num_patches"]
return [e.flatten(0, 1) for e in image_features.split(num_patches.tolist())]
The split() call fails because the computed num_patches value (17) does not match the actual tensor dimension (9):
RuntimeError: split_with_sizes expects split_sizes to sum exactly to 9
(input tensor's size at dimension 0), but got split_sizes=[17]
This unhandled exception terminates the EngineCore process, crashing the server.
Affected Models
Any model using the Idefics3 architecture. The vulnerability was tested with HuggingFaceTB/SmolVLM-Instruct.
Impact
Denial of service by crashing the engine
Mitigation
Validating the input:
def _validate_image_dimensions(self, image_shape):
h, w = image_shape[:2] if len(image_shape) == 3 else image_shape
if h < MIN_IMAGE_SIZE or w < MIN_IMAGE_SIZE:
raise ValueError(f"Image dimensions too small: {h}x{w}")
Managing the exception:
try:
return [e.flatten(0, 1) for e in image_features.split(num_patches.tolist())]
except RuntimeError as e:
logger.error(f"Image processing failed: {e}")
raise InvalidImageError("Failed to process image features") from e
Fixes
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | vllm | ≥ 0.6.4&&< 0.12.0 | 0.12.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for vllm. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update vllm to 0.12.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-grg2-63fw-f2qr is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-grg2-63fw-f2qr is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-grg2-63fw-f2qr. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-grg2-63fw-f2qr in your dependencies?
O3 detects GHSA-grg2-63fw-f2qr across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.