{"id":"PYSEC-2026-3411","summary":"vLLM has SSRF Protection Bypass","details":"## Summary\n\nThe 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.\n\n## Affected Component\n\n- **File**: `vllm/connections.py`\n- **Function**: `load_from_url_async`\n\n## Vulnerability Details\n\n### Root Cause\n\nThe 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.\n\nThese two URL parsers handle backslash characters (`\\`) differently:\n\n| Parser | Input URL | Parsed Host | Parsed Path | Behavior |\n|--------|-----------|-------------|-------------|----------|\n| `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 |\n| `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 |\n\n### Attack Scenario\n\n```python\n# Attacker provides this URL\nmalicious_url = \"https://httpbin.org\\\\@evil.com/\"\n\n# 1. Validation layer (urllib3.parse_url)\nparsed = urllib3.util.parse_url(malicious_url)\n# parsed.host == \"httpbin.org\"  ✅ Passes validation\n\n# 2. Actual request (aiohttp with yarl)\nasync with aiohttp.ClientSession() as session:\n    async with session.get(malicious_url) as response:\n        # Request actually goes to evil.com!  ❌ Bypass!\n```\n\n### Why This Happens\n\n1. **yarl**: Interprets `httpbin.org\\` as the userinfo component, and `@` as the userinfo/host separator, so the URL is parsed as `user=httpbin.org\\`, `host=evil.com`, `path=/`\n2. **urllib3**: URL-encodes the backslash as `%5C`, so `\\@evil.com/` becomes `/%5C@evil.com/` which is treated as part of the path, leaving `host=httpbin.org`\n\nThis inconsistency allows an attacker to:\n- Bypass the hostname allowlist check\n- Access arbitrary internal/external services\n- Perform full SSRF attacks\n\n## Fixes\n\n- https://github.com/vllm-project/vllm/pull/34743","aliases":["CVE-2026-25960","GHSA-v359-jj2v-j536"],"modified":"2026-07-13T16:32:59.515986720Z","published":"2026-07-13T14:36:41.656820Z","references":[{"type":"WEB","url":"https://github.com/vllm-project/vllm/security/advisories/GHSA-qh4c-xf7m-gxfc"},{"type":"WEB","url":"https://github.com/vllm-project/vllm/security/advisories/GHSA-v359-jj2v-j536"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-25960"},{"type":"WEB","url":"https://github.com/vllm-project/vllm/pull/34743"},{"type":"WEB","url":"https://github.com/vllm-project/vllm/commit/6f3b2047abd4a748e3db4a68543f8221358002c0"},{"type":"PACKAGE","url":"https://github.com/vllm-project/vllm"},{"type":"PACKAGE","url":"https://pypi.org/project/vllm"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-v359-jj2v-j536"}],"affected":[{"package":{"name":"vllm","ecosystem":"PyPI","purl":"pkg:pypi/vllm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.15.1"},{"fixed":"0.17.0"}]}],"versions":["0.15.1","0.16.0"],"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/vllm/PYSEC-2026-3411.yaml"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L"}]}