CVE-2025-70517

Executive Summary

CVE-2025-70517 is a Cross-Site Request Forgery (CSRF) vulnerability affecting Fanvil x7a IP desk phone firmware version 2.6.0.1182. The device's HTTP request handler fails to enforce any cross-origin resource protection mechanism for state-changing requests, enabling an attacker to bypass the same-origin policy boundary entirely and forge arbitrary requests against any application endpoint on the device. Any enterprise deploying Fanvil x7a handsets running firmware 2.6.0.1182 is affected; successful exploitation can result in unauthorized configuration changes, credential manipulation, or device reconfiguration without the victim's knowledge.

Technical Analysis

The vulnerability resides in the HTTP request handler of the Fanvil x7a firmware (version 2.6.0.1182). According to the NVD description, the request handler "does not enforce any cross-origin resource protection for any state-changing request performed against the applications."

This is a classic CWE-352 (Cross-Site Request Forgery) condition. The fundamental mechanism is as follows: web browsers enforce the Same-Origin Policy (SOP) to prevent scripts loaded from one origin from reading responses or initiating requests to a different origin. Anti-CSRF protections — such as unpredictable tokens, SameSite cookie attributes, Origin/Referer header validation, or custom request headers — are the standard defenses that a web application must implement to prevent a malicious third-party page from silently issuing authenticated requests on behalf of a logged-in user.

In this case, the Fanvil x7a firmware's HTTP handler lacks all such controls for state-changing requests. This means:

1. No anti-CSRF token validation: The handler does not require or verify a per-session or per-request token that a cross-origin attacker could not predict.
2. No Origin/Referer enforcement: The handler does not validate the Origin or Referer HTTP headers to confirm the request originated from the device's own web interface.
3. No SameSite cookie enforcement: Session cookies used for authentication to the web management interface are not restricted from being sent on cross-site requests.

The vulnerability affects the device's web-based management and application layer, which is typically accessible over the local network on HTTP (port 80) or HTTPS (port 443). Because the request handler processes state-changing requests without cross-origin protection, an attacker who can persuade an authenticated administrator to visit a malicious web page will have their browser silently issue forged requests to the Fanvil x7a device.

The NVD description explicitly states the cross-origin boundary "can be completely bypassed," indicating that the flaw is not limited to a single endpoint but applies to "any state-changing request performed against the applications." This broad scope significantly amplifies the severity — every administrative action exposed by the firmware's HTTP interface is potentially forgeable.

No CVSS score, CWE mapping, or vendor advisory was provided in the source data. The CWE-352 classification is assigned here based on the described mechanism, and the CVSS vector is an estimate derived from the vulnerability class (network-accessible, low complexity, no privileges required, user interaction required, high integrity impact).

Exploitation Scenarios

Note: No public proof-of-concept, exploit code, or Nuclei template is available for CVE-2025-70517. The attack chain described below is inferred from the CSRF vulnerability class and the NVD description. No specific function names, URL endpoints, API paths, or parameter names are provided because none appear in the available source data.

1. Reconnaissance / Target Identification An attacker identifies Fanvil x7a devices on a network. Because these are enterprise VoIP handsets, they are typically deployed in large numbers across corporate LANs. An attacker with network access (e.g., a compromised workstation, a rogue device on the LAN, or a malicious insider) can fingerprint the devices by their HTTP management interface. In a broader campaign, an attacker may target victims via phishing to reach devices that are exposed or reachable from the victim's browser context.

2. Triggering the Flaw The attacker crafts a malicious web page or HTML email containing a forged state-changing request directed at the Fanvil x7a device's IP address. The victim — an authenticated administrator or user of the device's web interface — is induced to load this page in their browser. Because the device's request handler enforces no cross-origin resource protection, the browser transmits the forged request with the victim's session cookie included, and the device processes it as if it were a legitimate local request.

No cross-origin token, Origin check, Referer validation, or SameSite cookie restriction stands in the way. The request succeeds silently without the victim's awareness.

3. Payload / Execution (Vulnerability-Class Level) At the vulnerability-class level, the payload is an HTML form submission or an asynchronous JavaScript request (e.g., fetch or XMLHttpRequest) embedded in the attacker's page. Because the handler does not validate request origin or require an unpredictable token, any state-changing action the device's web application exposes can be triggered. The attacker does not need to know a specific endpoint name to describe the mechanism — the flaw is that any state-changing endpoint is forgeable.

4. Post-Exploitation Impact Successful CSRF against an IP phone's management interface can lead to:

• Credential manipulation: Changing the administrator password, SIP registration credentials, or provisioning server details.
• Configuration tampering: Altering call routing, speed-dial entries, or auto-provisioning URLs to redirect the device to an attacker-controlled server.
• Eavesdropping enablement: Modifying SIP server settings to route calls through an attacker-controlled proxy, facilitating call interception.
• Denial of service: Resetting the device, corrupting configuration, or disabling network services.

Because the flaw applies to "any state-changing request," the blast radius within a single device is essentially the entire management API surface.

Impact Assessment

Affected Systems: Fanvil x7a IP desk phones running firmware version 2.6.0.1182. These devices are common in enterprise VoIP deployments, call centers, and unified communications environments.

Business Impact: The integrity impact is high. An attacker who successfully exploits this CSRF flaw can modify device configuration, potentially intercepting or redirecting voice communications, altering SIP credentials, or enrolling the device into an attacker-controlled provisioning infrastructure. This can lead to telecom fraud, eavesdropping on sensitive business calls, and lateral movement within the VoIP network.

CVSS Subscores (Estimated — no official score provided):

• Attack Vector (AV:N): Network — the device's web interface is reachable over the network.
• Attack Complexity (AC:L): Low — no special conditions beyond user interaction.
• Privileges Required (PR:N): None — the attacker needs no account on the device.
• User Interaction (UI:R): Required — the victim must load the attacker's page while authenticated to the device.
• Scope (S:U): Unchanged — the vulnerable component and impacted component are the same device.
• Confidentiality (C:N): No direct confidentiality impact from the forgery itself.
• Integrity (I:H): High — arbitrary configuration changes are possible.
• Availability (A:N): No direct availability impact, though configuration changes could degrade service.

Blast Radius: Within an enterprise, every Fanvil x7a device on the same network segment running the vulnerable firmware is at risk. Mass exploitation via a single malicious page is feasible if multiple devices are reachable from the victim's browser. The absence of a patch (Patch Confidence: 0/4) means the exposure persists indefinitely without compensating controls.

Exploit Maturity: No public PoC, exploit code, or Nuclei template is available. CISA KEV does not list this CVE. No known threat actor campaigns or in-the-wild exploitation has been reported. Exploitation is currently theoretical but trivial to construct given the vulnerability class.

Detection Guidance

Sigma Rule

title: Fanvil X7A CSRF State-Changing Request Detection
id: 8f3c2a1e-7051-4b9d-a2c7-1e6f0d3b9c44
status: experimental
description: Detects potential cross-site request forgery attempts against Fanvil x7a firmware web management interface where state-changing requests lack expected origin validation.
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2025-70517
author: Valters IT Threat Intelligence
date: 2025/05/20
tags:
  - attack.t1189
  - cve.2025.70517
logsource:
  category: webserver
  product: fanvil
detection:
  selection_method:
    cs-method:
      - 'POST'
      - 'PUT'
      - 'DELETE'
      - 'PATCH'
  selection_missing_origin:
    - cs-headers|contains: 'Origin'
  selection_missing_referer:
    - cs-headers|contains: 'Referer'
  condition: selection_method and (not selection_missing_origin or not selection_missing_referer)
falsepositives:
  - Legitimate API clients that do not send Origin or Referer headers
  - Automated provisioning tools
level: medium

YARA Rule

rule CVE_2025_70517_Fanvil_X7A_CSRF
{
    meta:
        description = "Detects Fanvil x7a firmware 2.6.0.1182 web handler lacking CSRF protection"
        author = "Valters IT Threat Intelligence"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-70517"
        date = "2025-05-20"
        severity = "medium"

    strings:
        $fw_ver = "2.6.0.1182" ascii wide
        $fanvil = "Fanvil" ascii wide nocase
        $x7a = "X7A" ascii wide
        $csrf_absent1 = "X-CSRF-Token" ascii wide nocase
        $csrf_absent2 = "csrf_token" ascii wide nocase
        $samesite = "SameSite" ascii wide nocase

    condition:
        $fanvil and $x7a and $fw_ver and not any of ($csrf_absent*)
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2025-70517 Fanvil X7A CSRF State-Changing Request Without Origin"; flow:established,to_server; http.method; content:"POST"; http.header; content:!"Origin"; http.header; content:!"Referer"; http.user_agent; content:"Mozilla"; classtype:attempted-admin; reference:cve,2025-70517; reference:url,nvd.nist.gov/vuln/detail/CVE-2025-70517; sid:202570517; rev:1;)

Elastic Detection

network where
  network.transport == "tcp" and
  network.direction == "outbound" and
  http.request.method in ("POST", "PUT", "DELETE", "PATCH") and
  not http.request.headers contains "Origin" and
  not http.request.headers contains "Referer" and
  (destination.port == 80 or destination.port == 443)

Splunk SPL Query

index=network sourcetype=stream:http
| search http_method IN ("POST","PUT","DELETE","PATCH")
| eval has_origin=if(like(http_headers, "%Origin%"), 1, 0)
| eval has_referer=if(like(http_headers, "%Referer%"), 1, 0)
| where has_origin=0 AND has_referer=0
| stats count BY src_ip, dest_ip, dest_port, uri_path, http_method
| where count > 0
| sort - count

Wazuh OSSEC Rule

<group name="fanvil,csrf,">
  <rule id="100517" level="10">
    <decoded_as>json</decoded_as>
    <field name="http_method">POST|PUT|DELETE|PATCH</field>
    <field name="http_headers" negate="yes">Origin</field>
    <field name="http_headers" negate="yes">Referer</field>
    <description>CVE-2025-70517: Fanvil X7A state-changing request without Origin/Referer header - potential CSRF</description>
    <mitre>
      <id>T1189</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch Confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source). No vendor fix, firmware update, or workaround has been published. The following steps are recommended:

1. Immediate Mitigations

• Network isolation: Place Fanvil x7a devices on a dedicated VLAN, isolated from general user workstations and the public internet. Restrict management interface access to a dedicated administrative subnet.
• Disable web management if unused: If the HTTP/HTTPS management interface is not required for operations, disable it entirely.
• Restrict browser access: Prevent administrative browsers from visiting untrusted websites while authenticated to the device interface. Enforce a dedicated, locked-down browser session for device management.
• Firewall rules: Block inbound access to the device web interface from user VLANs; allow only from jump hosts or management systems.
• Logout discipline: Administrators should log out of the device web interface immediately after completing management tasks to invalidate sessions.

2. Patch / Upgrade Steps

• Monitor Fanvil's official security advisory and firmware release channels for a fixed firmware version addressing CVE-2025-70517.
• Contact Fanvil support to request a patch timeline or interim guidance.
• Do not rely on unofficial firmware or third-party modifications.

3. Long-Term Hardening

• Implement a device management policy that requires all administrative interfaces to be accessed only over an isolated management network.
• Deploy network monitoring (Suricata, Zeek) with the detection rules above to alert on suspicious state-changing requests to VoIP device interfaces.
• Enforce browser hardening policies (e.g., enterprise policy blocking third-party cookies; though this does not fully mitigate the absence of Origin validation).
• Conduct a vendor risk assessment for Fanvil products and evaluate alternative devices with demonstrated CSRF protections.
• Include VoIP device firmware in vulnerability management scanning and asset inventory.

References

1. NVD — CVE-2025-70517: https://nvd.nist.gov/vuln/detail/CVE-2025-70517
2. MITRE CWE-352 — Cross-Site Request Forgery: https://cwe.mitre.org/data/definitions/352.html
3. MITRE ATT&CK T1189 — Drive-by Compromise: https://attack.mitre.org/techniques/T1189/
4. OWASP — Cross-Site Request Forgery Prevention Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Cross-Site_Request_Forgery_Prevention_Cheat_Sheet.html
5. CISA Known Exploited Vulnerabilities Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog (CVE-2025-70517 not listed as of report date)

Threat Actor / Exploit-in-the-Wild Status: No known threat actor campaigns, public proof-of-concept exploits, or in-the-wild exploitation evidence has been identified for CVE-2025-70517. The CVE is not listed in CISA KEV, no Nuclei template exists, and no exploit code has been published. The vulnerability remains unpatched with no vendor advisory available at the time of writing.