CVE-2025-46560 – vllm

Package

Manager: pip
Name: vllm
Vulnerable Version: >=0.8.0 <0.8.5

Severity

Level: Medium

CVSS v3.1: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

EPSS: 0.00081 pctl0.24594

Details

phi4mm: Quadratic Time Complexity in Input Token Processing​ leads to denial of service ### Summary A critical performance vulnerability has been identified in the input preprocessing logic of the multimodal tokenizer. The code dynamically replaces placeholder tokens (e.g., <|audio_*|>, <|image_*|>) with repeated tokens based on precomputed lengths. Due to ​​inefficient list concatenation operations​​, the algorithm exhibits ​​quadratic time complexity (O(n²))​​, allowing malicious actors to trigger resource exhaustion via specially crafted inputs. ### Details ​​Affected Component​​: input_processor_for_phi4mm function. https://github.com/vllm-project/vllm/blob/8cac35ba435906fb7eb07e44fe1a8c26e8744f4e/vllm/model_executor/models/phi4mm.py#L1182-L1197 The code modifies the input_ids list in-place using input_ids = input_ids[:i] + tokens + input_ids[i+1:]. Each concatenation operation copies the entire list, leading to O(n) operations per replacement. For k placeholders expanding to m tokens, total time becomes O(kmn), approximating O(n²) in worst-case scenarios. ### PoC Test data demonstrates exponential time growth: ```python test_cases = [100, 200, 400, 800, 1600, 3200, 6400] run_times = [0.002, 0.007, 0.028, 0.136, 0.616, 2.707, 11.854] # seconds ``` Doubling input size increases runtime by ~4x (consistent with O(n²)). ### Impact ​​Denial-of-Service (DoS):​​ An attacker could submit inputs with many placeholders (e.g., 10,000 <|audio_1|> tokens), causing CPU/memory exhaustion. Example: 10,000 placeholders → ~100 million operations. ### Remediation Recommendations​ Precompute all placeholder positions and expansion lengths upfront. Replace dynamic list concatenation with a single preallocated array. ```python # Pseudocode for O(n) solution new_input_ids = [] for token in input_ids: if token is placeholder: new_input_ids.extend([token] * precomputed_length) else: new_input_ids.append(token) ```

Metadata

Created: 2025-04-29T16:43:10Z
Modified: 2025-04-30T17:27:16Z
Source: https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/04/GHSA-vc6m-hm49-g9qg/GHSA-vc6m-hm49-g9qg.json
CWE IDs: ["CWE-1333"]
Alternative ID: GHSA-vc6m-hm49-g9qg
Finding: F211
Auto approve: 1