CVE-2026-25960

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 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:

Attack Scenario

# 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 /%[email protected]/ 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

Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.

CVE-2026-25960 has a CVSS score of 5.4 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.17.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-25960? CVE-2026-25960 is a medium-severity server-side request forgery (SSRF) vulnerability in vllm (pip), affecting versions >= 0.15.1, < 0.17.0. It is fixed in 0.17.0. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
2. How severe is CVE-2026-25960? CVE-2026-25960 has a CVSS score of 5.4 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of vllm are affected by CVE-2026-25960? vllm (pip) versions >= 0.15.1, < 0.17.0 is affected.
4. Is there a fix for CVE-2026-25960? Yes. CVE-2026-25960 is fixed in 0.17.0. Upgrade to this version or later.
5. Is CVE-2026-25960 exploitable, and should I be worried? Whether CVE-2026-25960 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-25960 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-25960? Upgrade vllm to 0.17.0 or later.