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Response snapshot Oct 29, 2026, 01:26 UTC

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VulnerabilityCVE-2026-115917

vLLM: Permissive default CORS origins allow cross-origin requests to the vLLM HTTP server

The OpenAI-compatible server registers Starlette CORSMiddleware with allowed_origins defaulting to ["*"], and performs no authentication unless --api-key (or VLLM_API_KEY) is configured.

At a glance

Exploited
Not known
Severity
3.4 Low (CVSS 3.1)
Chance of exploitation
Not estimated
Sources
1 source

What to do

GitHub lists first patched versions: vllm: 0.32.0. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-vvpg-rrww-wpmh (opens a new tab)

What happened

Summary

The OpenAI-compatible server registers Starlette CORSMiddleware with allowed_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 example localhost or an internal/VPN address) and read the responses.

The default allow_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

Continue reading

Affected components

- vllm/entrypoints/launchers/cli_args.py - allowed_origins default 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), issue POST /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](https://github.com/vllm-project/vllm/pull/61009).

Affected package ranges reported by GitHub: vllm: < 0.32.0

Scores and how they were measured

CVSS base severity

3.4

Version 3.1As of

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-vvpg-rrww-wpmh (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-vvpg-rrww-wpmh, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 28). vLLM: Permissive default CORS origins allow cross-origin requests to the vLLM HTTP server (CVE-2026-115917). https://kevwire.com/record/CVE-2026-115917

MLA

"vLLM: Permissive default CORS origins allow cross-origin requests to the vLLM HTTP server (CVE-2026-115917)." KEVWire, 28 Oct. 2026, kevwire.com/record/CVE-2026-115917.

Chicago

KEVWire. "vLLM: Permissive default CORS origins allow cross-origin requests to the vLLM HTTP server (CVE-2026-115917)." Last modified October 28, 2026. https://kevwire.com/record/CVE-2026-115917.

Evidence summary (plain text)

vLLM: Permissive default CORS origins allow cross-origin requests to the vLLM HTTP server (Oct 28, 2026).
The OpenAI-compatible server registers Starlette CORSMiddleware with
allowed_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 example
localhost or an internal/VPN address) and read the responses.
CVSS 3.4 (version 3.1; evidence as of Oct 28, 2026; https://github.com/advisories/GHSA-vvpg-rrww-wpmh).
Sources:
GitHub-reviewed advisory GHSA-vvpg-rrww-wpmh: https://github.com/advisories/GHSA-vvpg-rrww-wpmh
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc
Record ID: CVE-2026-115917.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 29, 2026, 00:55 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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Record details

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