Affected: vllm-project vllm, Red Hat OpenShift AI 2.25, Red Hat AI Inference Server, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI)

vLLM is an inference and serving engine for large language models (LLMs). The SSRF protection fix for CVE-2026-24779 add in 0.15.1 can be bypassed in the load_from_url_async method due to inconsistent URL parsing behavior between the validation layer and the actual HTTP client. The SSRF fix uses urllib3.util.parse_url() to validate and extract the hostname from user-provided URLs. However, load_from_url_async uses aiohttp for making the actual HTTP requests, and aiohttp internally uses the yarl library for URL parsing. This vulnerability in 0.17.0.

Affected: PyPI: vllm

## Summary

The SSRF protection fix for https://github.com/vllm-project/vllm/security/advisories/GHSA-qh4c-xf7m-gxfc can be bypassed in the `load_from_url_async` method due to inconsistent URL parsing behavior between the validation layer and the actual HTTP client.

## Affected Component

- **File**: `vllm/connections.py` - **Function**: `load_from_url_async`

## Vulnerability Details

### Root Cause

The SSRF [fix](https://github.com/vllm-project/vllm/pull/32746) uses `urllib3.util.parse_url()` to validate and extract the hostname from user-provided URLs. However, `load_from_url_async` uses `aiohttp` for making the actual HTTP requests, and `aiohttp` internally uses the `yarl` library for URL parsing.

These two URL parsers handle backslash characters (`\`) differently:

| Parser | Input URL | Parsed Host | Parsed Path | Behavior | |--------|-----------|-------------|-------------|----------| | `urllib3.parse_url()` | `https://httpbin.org\@evil.com/` | `httpbin.org` | `/%5C@evil.com/` | URL-encodes `\` as `%5C`, treats `\@evil.com/` as part of the path | | `yarl` (via aiohttp) | `https://httpbin.org\@evil.com/` | `evil.com` | `/` | Treats `\` as part of userinfo (`user: httpbin.org\`), the `@` acts as the userinfo/host separator |

### Attack Scenario

```python # Attacker provides this URL malicious_url = "https://httpbin.org\\@evil.com/"

# 1. Validation layer (urllib3.parse_url) parsed = urllib3.util.parse_url(malicious_url) # parsed.host == "httpbin.org" ✅ Passes vali…