CVE-2025-48956Public exploitNetwork attack vector

Unauthenticated crash via unbounded HTTP headers

Published Aug 21, 2025 · Updated Aug 21, 2025

Uncontrolled resource consumption in vLLM 0.1.0 through 0.10.1 allows remote attackers to crash or hang its API server via oversized HTTP headers. The serve_http path passes requests to Uvicorn's h11 parser without limits on incomplete-event size or header count, so a multi-gigabyte X-Forwarded-For value is loaded into server memory. No authentication or user interaction is required; one remotely delivered request can exhaust memory and leave the serving process crashed or unresponsive.

CVSS severity7.5
High
EPSS probability0.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in vLLM 0.1.0 through 0.10.1 allows remote attackers to crash or hang its API server via oversized HTTP headers. The serve_http path passes requests to Uvicorn's h11 parser without limits on incomplete-event size or header count, so a multi-gigabyte X-Forwarded-For value is loaded into server memory. No authentication or user interaction is required; one remotely delivered request can exhaust memory and leave the serving process crashed or unresponsive.

The record

CVE
CVE-2025-48956
Published
Aug 21, 2025
Updated
Aug 21, 2025
Vendor
vLLM Project
Product
vLLM
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 21, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 0.1.0, < 0.10.1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

vLLM Project · vLLMversion=>= 0.1.0, < 0.10.1.1

Published CVSS scores

7.5GitHub CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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