CVE-2025-70518

Executive Summary

CVE-2025-70518 is an unauthenticated OS command injection vulnerability in the management portal's diagnostic ping tool of Fanvil x7a IP phones running firmware version 2.6.0.1182. Because the device fails to handle user-supplied input securely, any network-reachable attacker can inject arbitrary commands that execute with the privileges of the underlying Android operating system. Successful exploitation yields full compromise of the phone, including access to configuration data, credentials, and the ability to pivot into the enterprise voice network; no patch is currently available.

Technical Analysis

Fanvil x7a devices are enterprise-class SIP desk phones built on an Android operating system base and managed through an embedded web management portal. That portal exposes a diagnostic ping utility — a common administrative convenience feature that takes a user-supplied hostname or IP address and passes it to the operating system's network diagnostic facility to test reachability.

The vulnerability resides in that diagnostic ping tool. According to the NVD description, the component "does not handle user supplied input securely," which "allows any unauthenticated attacker to inject commands and run code in the underlying Android operating system."

At the vulnerability-class level, this is OS command injection (CWE-78). The mechanism is well understood: the management portal constructs a shell command by concatenating the attacker-controlled ping target string into a command line and invoking a system shell, without validating, sanitizing, or escaping shell metacharacters. Because input is neither constrained to a valid hostname/IP syntax nor passed through an argument-vector API (which would avoid shell interpretation entirely), characters such as command separators or substitution operators are interpreted by the shell rather than treated as literal data. The injected portion of the string is therefore executed as an additional command on the device.

Several characteristics make this particularly severe:

• No authentication required. The description states "any unauthenticated attacker" can exploit the flaw. This means the vulnerability is not gated behind administrative credentials, so exposure of the management portal to any untrusted network segment is sufficient for exploitation.
• Execution context is the underlying Android OS. Injected commands do not run inside a restricted web sandbox; they run as OS-level processes on the Android host. This grants the attacker the effective privileges of the web service process and access to the Android filesystem, process table, network stack, and any services running on the device.
• Attack surface is the management portal. The management portal is by design network-facing — it is reached over the LAN, management VLAN, or WAN depending on deployment. The diagnostic ping tool is part of the normal administrative interface, so the vulnerable code path is reachable through ordinary HTTP/HTTPS requests to the device.

The absence of a CNA-supplied title, CWE mapping, CVSS score, and affected-version list in the source data means the CVE record is sparse. No specific parameter names, endpoint paths, or code symbols for the ping handler are provided in the NVD description, and this report does not invent them. The vulnerability class (unauthenticated OS command injection via a web diagnostic utility) is, however, unambiguous from the description, and the exploitation model below is derived strictly from that class and the stated facts.

Exploitation Scenarios

No public proof-of-concept, exploit code, or Nuclei template is available for CVE-2025-70518. The attack chain below is inferred from the vulnerability class (unauthenticated OS command injection in a web management diagnostic tool) and the facts stated in the NVD description. No specific function names, endpoints, or parameters are fabricated.

1. Reconnaissance / target identification. An attacker enumerates the network for Fanvil x7a devices by fingerprinting the management portal (for example via HTTP response banners, page titles, or device-specific headers). Devices with firmware 2.6.0.1182 and a reachable management portal are viable targets. Exposure may be on the corporate LAN, a voice VLAN, a guest network that can route to the management interface, or — in misconfigured deployments — the public internet.

2. Triggering the flawed component. The attacker locates the diagnostic ping tool within the management portal. Critically, per the NVD description, no authentication is required, so no credential-gathering or session-establishment step is needed. The attacker simply submits input to the ping tool's user-supplied field.

3. Injection at the vulnerability-class level. Instead of a valid hostname or IP address, the attacker supplies a value containing shell metacharacters. Because the portal does not handle the input securely, the metacharacters are not treated as literal data but are interpreted by the underlying shell, causing the injected command to execute on the Android OS. The exact injection string and any required escaping depend on implementation details not disclosed in the CVE record; the general technique — breaking out of the intended command context with shell control operators — is the standard exploitation pattern for this class.

4. Post-exploitation impact. Because injected commands run in the underlying Android operating system, the attacker obtains command execution on the phone itself. From there, realistic objectives include reading device and configuration data (including any credentials or SIP registration secrets stored on the device), manipulating phone behavior, establishing persistence, using the device as a foothold to reach other hosts on the voice or management network, and exfiltrating data to an attacker-controlled endpoint. Full impact on confidentiality, integrity, and availability of the device follows from OS-level code execution.

Impact Assessment

CVE-2025-70518 carries no published CVSS score in the source data; the vector above (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) reflects the description's stated properties — network-reachable, low complexity, no privileges, no user interaction — and is provided as an analytic assessment rather than a vendor- or NVD-published figure. CWE-78 is likewise assigned here based on the described mechanism, not supplied by the CVE record. There is no CISA KEV listing and no EPSS score has been assigned by FIRST.org.

Business impact. Fanvil x7a phones are enterprise desk phones deployed at scale in offices, call centers, and branch locations. Compromise of a single device yields an OS-level foothold inside the corporate network — specifically in the voice segment, which is frequently under-monitored relative to general IT. Because the flaw is unauthenticated, any host that can reach the management portal can attempt exploitation without credentials or prior access.

Affected systems. The explicitly identified affected configuration is Fanvil x7a firmware version 2.6.0.1182. No broader version range is stated in the source data. Organizations should inventory all Fanvil x7a endpoints and confirm their firmware level rather than assuming the issue is limited to that exact build.

Blast radius. Each vulnerable device is an independently exploitable node. An attacker who compromises one phone can harvest on-device secrets, monitor or manipulate voice traffic reachable from that device, and use it as a pivot point toward other systems on the same network segments. In environments where the management portal is exposed beyond a tightly controlled administrative VLAN, the effective blast radius extends to anyone who can route packets to the device. The confidentiality, integrity, and availability of the device are all fully impacted, with potential secondary impact to adjacent network assets.

Detection Guidance

Detection for this vulnerability centers on two surfaces: the exploit attempt itself (malicious input to the diagnostic ping tool, observable in web/proxy/IDS telemetry) and the post-exploitation behavior (shell command execution on the device). Because the management portal's exact URL path and parameter are not disclosed in the CVE record, the rules below key on the presence of shell metacharacters in requests to Fanvil management interfaces and on anomalous process/network behavior on the device, rather than on invented parameter names.

Sigma Rule

title: Fanvil x7a Management Portal Diagnostic Ping Command Injection Attempt
id: 7c1f2a90-3b6e-4d21-9a5f-5e8d4b0c1a77
status: experimental
description: Detects shell metacharacters in HTTP requests to Fanvil x7a management portals, indicative of OS command injection against the diagnostic ping tool (CVE-2025-70518).
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2025-70518
author: valtersit.com
date: 2025-01-01
logsource:
  category: webserver
  product: fanvil
detection:
  selection_target:
    cs-uri-query|contains:
      - 'ping'
      - 'diag'
      - 'diagnostic'
  selection_metachars:
    cs-uri-query|contains:
      - ';'
      - '|'
      - '&&'
      - '`'
      - '$('
      - '>'
      - '<'
      - '%0a'
      - '%3b'
      - '%7c'
  condition: selection_target and selection_metachars
falsepositives:
  - Legitimate administrative diagnostics containing unusual hostnames
level: high
tags:
  - attack.t1190
  - cwe.78

YARA Rule

rule CVE_2025_70518_Fanvil_x7a_CommandInjection
{
    meta:
        description = "Detects fanvil x7a firmware 2.6.0.1182 management portal binaries referencing the diagnostic ping tool and OS command execution, relevant to CVE-2025-70518"
        author = "valtersit.com"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-70518"
        date = "2025-01-01"
        severity = "high"

    strings:
        $firmware = "2.6.0.1182" ascii wide
        $ping     = "ping" ascii wide nocase
        $diag     = "diagnostic" ascii wide nocase
        $sh       = "/system/bin/sh" ascii wide
        $sh2      = "sh -c" ascii wide
        $exec     = "Runtime.getRuntime" ascii wide
        $exec2    = "ProcessBuilder" ascii wide

    condition:
        uint16(0) == 0x5A4D or uint32(0) == 0x464C457F or filesize < 20MB
        and ( $firmware or ( $ping and $diag ) )
        and ( $sh or $sh2 or $exec or $exec2 )
}

Suricata IDS Rule

alert http any any -> any any (msg:"CVE-2025-70518 Fanvil x7a Diagnostic Ping Command Injection Attempt"; flow:to_server,established; http.method; content:"GET"; http.uri; content:"ping"; nocase; http.uri; pcre:"/(%3b|%7c|%26%26|%60|%24%28|;|\||&&|`|\$\().*(ping|diag)/i"; reference:cve,2025-70518; reference:url,nvd.nist.gov/vuln/detail/CVE-2025-70518; classtype:web-application-attack; sid:202570518; rev:1;)

Elastic Detection

sequence by host.ip with maxspan=5s
  [network where network.protocol == "http" and
    http.request.method == "GET" and
    wildcard(http.request.uri, "*ping*") and
    (wildcard(http.request.uri, "*;*") or
     wildcard(http.request.uri, "*|*") or
     wildcard(http.request.uri, "*%3b*") or
     wildcard(http.request.uri, "*%7c*") or
     wildcard(http.request.uri, "*%60*") or
     wildcard(http.request.uri, "*%24%28*"))]

Splunk SPL Query

index=web OR index=proxy sourcetype=access_combined OR sourcetype=*proxy*
| eval uri_lower = lower(uri)
| where (like(uri_lower, "%ping%") OR like(uri_lower, "%diag%"))
| where (like(uri_lower, "%;%") OR like(uri_lower, "%|%")
         OR like(uri_lower, "%`%") OR like(uri_lower, "%$(%")
         OR like(uri_lower, "%&&%"))
| stats count values(uri) as suspicious_uris by src_ip, dest_ip, http_user_agent
| sort - count

Wazuh OSSEC Rule

<group name="web,fanvil,cve-2025-70518,">
  <rule id="100518" level="12">
    <if_sid>31100</if_sid>
    <match>ping|diag|diagnostic</match>
    <regex>(\;|\||\&\&|`|\$\(|%3b|%7c|%24%28)</regex>
    <description>CVE-2025-70518: Possible OS command injection against Fanvil x7a management portal diagnostic ping tool</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>cve_2025_70518,command_injection,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 — UNPATCHED. No patch, fixed firmware version, or vendor advisory has been identified from any tracked source. There is no vendor fix and no documented workaround in the source data. The recommendations below are standard hardening measures for an unpatched, unauthenticated OS command injection in a network-facing management interface; they are defensive controls, not vendor-provided fixes.

1) Immediate mitigations

• Remove network reachability. Restrict the Fanvil x7a management portal to a dedicated, strictly firewalled administrative VLAN. Block access to the portal from user VLANs, guest networks, and especially the public internet. The vulnerability requires only network reachability, so network isolation is the single most effective control available while unpatched.
• Inventory and confirm exposure. Identify every Fanvil x7a device and determine which of them run firmware 2.6.0.1182 or otherwise expose the diagnostic ping tool. Devices on 2.6.0.1182 with reachable management interfaces should be treated as at-risk.
• Disable the diagnostic ping tool if possible. If the management portal permits disabling diagnostic utilities, do so. Removing the reachable vulnerable component eliminates the attack path even if the code remains unpatched.
• Harden administrative access. Require authentication for all management functions where the platform allows it, apply management-interface ACLs, and avoid exposing the portal on any routable public address.
• Segment the voice network. Ensure VoIP endpoints cannot initiate arbitrary connections to sensitive IT segments, limiting the value of a compromised phone as a pivot.

2) Patch / upgrade steps

• Monitor Fanvil's official support and security channels for a firmware release addressing CVE-2025-70518. As of this report, no fixed version is known.
• When a vendor firmware update is published, validate it in a controlled environment, then upgrade all affected x7a devices in a scheduled maintenance window and verify the firmware version post-upgrade.
• Document the firmware baseline for all voice endpoints so future vulnerable builds can be identified quickly.

3) Long-term hardening

• Treat IP phones and other voice endpoints as untrusted network devices: place them on segmented VLANs with least-privilege firewall rules between the voice segment and IT/OT networks.
• Enforce a recurring firmware-vulnerability management process for all telephony hardware, including automated inventory of firmware versions.
• Disable or restrict unnecessary management and diagnostic features on network appliances and IoT endpoints by default.
• Apply egress filtering so a compromised endpoint cannot freely reach arbitrary external hosts.
• Maintain monitoring for command-injection patterns against management interfaces (see Detection Guidance) so exploitation attempts are detected even without a patch.

References

1. NVD — CVE-2025-70518: https://nvd.nist.gov/vuln/detail/CVE-2025-70518
2. MITRE ATT&CK — T1190, Exploit Public-Facing Application: https://attack.mitre.org/techniques/T1190/
3. CWE-78 — Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'): https://cwe.mitre.org/data/definitions/78.html
4. Fanvil official product and support portal (monitor for a security advisory covering x7a firmware): https://www.fanvil.com/
5. FIRST.org EPSS (no score currently assigned for CVE-2025-70518): https://www.first.org/epss/

No threat actor campaigns, exploit-in-the-wild activity, or CISA KEV listing are associated with CVE-2025-70518 in the available source data. No public PoC, exploit code, or Nuclei template exists at the time of writing; the attack chain described above is inferred from the vulnerability class stated in the NVD description.