Advisory details:
pypa / vllm/PYSEC-2026-3411
| Advisory ID | pypa/vllm/PYSEC-2026-3411 |
| Aliases |
CVE-2026-25960
GHSA-v359-jj2v-j536 PYSEC-2026-3411 |
| Summary | vLLM has SSRF Protection Bypass ## 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 validation # 2. Actual request (aiohttp with yarl) async with aiohttp.ClientSession() as session: async with session.get(malicious_url) as response: # Request actually goes to evil.com! ❌ Bypass! ``` ### Why This Happens 1. **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=/` 2. **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` This inconsistency allows an attacker to: - Bypass the hostname allowlist check - Access arbitrary internal/external services - Perform full SSRF attacks ## Fixes - https://github.com/vllm-project/vllm/pull/34743 |
| Status | Published |
| Exploitability | 0.5 |
| Weighted Severity | 4.9 |
| Risk | 2.5 |
| Affected and Fixed Packages | Package Details |
| Introduced and Fixed Package Commit Patches | Package Commit Patches Details |
| There are no known CWE. |
| System | Score | Found at |
|---|---|---|
| cvssv3.1 | 5.4 | https://github.com/pypa/advisory-database/blob/main/vulns/vllm/PYSEC-2026-3411.yaml |
| Reference id | Reference type | URL |
|---|---|---|
| https://github.com/vllm-project/vllm | ||
| https://pypi.org/project/vllm | ||
| 34743 | Other | https://github.com/vllm-project/vllm/pull/34743 |
| 6f3b2047abd4a748e3db4a68543f8221358002c0 | Other | https://github.com/vllm-project/vllm/commit/6f3b2047abd4a748e3db4a68543f8221358002c0 |
| CVE-2026-25960 | https://nvd.nist.gov/vuln/detail/CVE-2026-25960 | |
| GHSA-qh4c-xf7m-gxfc | https://github.com/vllm-project/vllm/security/advisories/GHSA-qh4c-xf7m-gxfc | |
| GHSA-v359-jj2v-j536 | https://github.com/advisories/GHSA-v359-jj2v-j536 | |
| GHSA-v359-jj2v-j536 | Other | https://github.com/vllm-project/vllm/security/advisories/GHSA-v359-jj2v-j536 |
No EPSS data available for this advisory.
| Patch URL | |
|---|---|
| There are no known patches. | |
| Attack Vector (AV) | Attack Complexity (AC) | Privileges Required (PR) | User Interaction (UI) | Scope (S) | Confidentiality Impact (C) | Integrity Impact (I) | Availability Impact (A) |
|---|---|---|---|---|---|---|---|
network adjacent_network local physical |
low high |
none low high |
none required |
unchanged changed |
high low none |
high low none |
high low none |
Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2026-03-10T15:01:11Z/
Decision: Track
Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2026/25xxx/CVE-2026-25960.json
Source Advisory: vulnrichment/CVE-2026-25960
[{'Exploitation': 'none'},
{'Automatable': 'no'},
{'Technical Impact': 'partial'},
{'Mission Prevalence': 'minimal'},
{'Public Well-being Impact': 'material'},
{'Mission & Well-being': 'medium'}]