Summary
vLLM: Permissive default CORS origins allow cross-origin requests to the vLLM HTTP server
The OpenAI-compatible server registers Starlette CORSMiddleware withallowed_origins defaulting to ["*"], and performs no authentication unless--api-key (or VLLM_API_KEY) is configured. A web page on any origin can send
requests to a vLLM server that the victim's browser can reach (for examplelocalhost or an internal/VPN address) and read the responses. The defaultallow_credentials=False blocks cookie-bearing cross-origin requests; because
vLLM authenticates with a bearer header rather than cookies, the wildcard still
permits untokenized access to an unauthenticated server and read access when the
caller already holds a token.
Details
Affected components
vllm/entrypoints/launchers/cli_args.py-allowed_originsdefault value.vllm/entrypoints/serve/middleware/register.py-CORSMiddleware
registration.vllm/entrypoints/serve/middleware/authenticate.py- auth middleware and its
guarded path prefixes.
Root cause
vllm/entrypoints/launchers/cli_args.py:
allow_credentials: bool = False
"""Allow credentials."""
allowed_origins: list[str] = field(default_factory=lambda: ["*"])
"""Allowed origins."""
vllm/entrypoints/serve/middleware/register.py:
app.add_middleware(
CORSMiddleware,
allow_origins=args.allowed_origins,
allow_credentials=args.allow_credentials,
allow_methods=args.allowed_methods,
allow_headers=args.allowed_headers,
)
The auth middleware is added only when a token is configured and guards only the/v1, /v2, /inference, and /cohere prefixes. /v1/load_lora_adapter and/v1/unload_lora_adapter are inside /v1 and therefore do require a key when
one is set; they are open only when no key is configured and dynamic LoRA
updating is enabled.
Impact
- A malicious page can enumerate models (
GET /v1/models), issuePOST /v1/chat/completions, consume GPU time, and read model output through
the victim's browser. - When the server is reachable only from the victim's network, the browser acts
as a proxy a remote website could not otherwise use. - With
allow_credentials=False, cookie-based CSRF does not apply; the exposure
is cross-origin request execution and response disclosure.
This advisory was fixed in MR61009.
CVE-2026-115917 has a CVSS score of 3.4 (Low). The vector is network-reachable, no privileges required, and user interaction required. 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 (0.32.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-115917? CVE-2026-115917 is a low-severity security vulnerability in vllm (pip), affecting versions < 0.32.0. It is fixed in 0.32.0.
- How severe is CVE-2026-115917? CVE-2026-115917 has a CVSS score of 3.4 (Low). 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.
- Which versions of vllm are affected by CVE-2026-115917? vllm (pip) versions < 0.32.0 is affected.
- Is there a fix for CVE-2026-115917? Yes. CVE-2026-115917 is fixed in 0.32.0. Upgrade to this version or later.
- Is CVE-2026-115917 exploitable, and should I be worried? Whether CVE-2026-115917 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
- What actually determines whether CVE-2026-115917 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.
- How do I fix CVE-2026-115917? Upgrade
vllmto 0.32.0 or later.