CVE-2026-82694

Executive Summary

CVE-2026-82694 is an unauthenticated remote vulnerability in the Tenda AC1206 router firmware version 15.03.06.23, specifically in the R7WebsSecurityHandler function of the /goform/ate file. The vulnerability allows a remote attacker to bypass all authentication checks, granting full control over the affected device without valid credentials. With a CVSS base score of 10.0 (Critical) and a public exploit available, any internet-exposed or network-accessible Tenda AC1206 running this firmware is at immediate risk of compromise. Successful exploitation enables an attacker to modify router configuration, intercept or redirect traffic, establish persistent backdoors, and use the device as a pivot point for lateral movement within the local network.

Technical Analysis

The vulnerability resides in the Web UI component of the Tenda AC1206 router, specifically within the handler R7WebsSecurityHandler. This function is invoked when requests are processed by the /goform/ate file path. The term "goform" indicates this is a CGI-style form handling mechanism commonly used in embedded networking devices built on the TR-069/Linux-based router stacks.

The flaw is classified as CWE-287 (Improper Authentication). The R7WebsSecurityHandler function fails to perform any authentication or session validation before processing incoming requests. In a correctly implemented router web interface, each form handler should verify that the requesting entity has an authenticated session (e.g., via cookie validation, session token verification, or IP-based locking). The absence of such a check in this handler means any HTTP request delivered to the /goform/ate endpoint is processed as if it originated from an authenticated administrative user.

The /goform/ate endpoint appears to be a diagnostic or test-related interface (the "ate" suffix often relates to Automated Test Equipment or factory diagnostics functions in router firmware). Such endpoints frequently contain debugging, configuration backup/restore, or firmware flashing capabilities. Because these endpoints are intended for factory testing, developers often omit authentication to simplify the test process — a classic insecure-by-design flaw that persists into production firmware.

Attack surface considerations: The attack can be initiated remotely over the network (AV:N). No privileges are required (PR:N), and no user interaction is needed (UI:N). The scope is changed (S:C), meaning a compromise of the router can affect resources beyond the device itself, such as the internal LAN. The confidentiality, integrity, and availability impacts are all rated High.

The NVD description provides no additional implementation details such as parameter names or specific payload requirements. It is reasonable to infer the attack is a simple HTTP POST or GET request to the affected endpoint without any session cookie or authentication header. Given the low attack complexity (AC:L), the exploitation mechanism is straightforward and does not require special conditions, race conditions, or complex input manipulation.

Exploitation Scenarios

Reconnaissance / Target Identification:
An attacker first identifies internet-exposed Tenda AC1206 routers. This is achievable through internet-wide scanning using search engines like Shodan, Censys, or through banner grabbing. Shodan dorks such as those listed in the metadata section (http.title:"AC1206", http.html:"Tenda") allow an attacker to generate a list of potentially vulnerable targets. Once a router is found, the attacker can verify the firmware version by accessing the web login page, which often displays the version string, or by fingerprinting the HTTP responses.

Triggering the Vulnerability:
The attacker crafts an HTTP request directed to the affected router's web interface. Based on the NVD description, the target is the /goform/ate path, which is handled by R7WebsSecurityHandler. The request requires no authentication token, cookie, or special header. The description indicates the issue is "missing authentication," meaning the handler processes the request without first verifying an authenticated session. A simple HTTP POST or GET to the /goform/ate endpoint is sufficient to trigger the vulnerability. No public PoC details are provided, so the exact HTTP method (GET vs. POST) and required parameters cannot be stated with certainty. Attack chain is inferred from the vulnerability class.

Payload / Execution Method (Vulnerability-Class Level):
Because this is a missing-authentication flaw in a web form handler, the attack operates at the application layer. The lack of authentication means the attacker can invoke any function exposed by the /goform/ate handler as if they were the administrative user. Typical capabilities exposed by such factory/diagnostic endpoints in router firmware include: reading or modifying system configuration, rebooting the device, restoring factory defaults, uploading new firmware, or executing diagnostic shell commands. The attacker sends form parameters corresponding to the desired action. Since CWE-287 is purely an authentication bypass (not a command injection or buffer overflow), the follow-on action depends entirely on what the handler exposes.

Post-Exploitation Impact:
Once authenticated access is obtained, the attacker achieves full administrative control of the router (C:H/I:H/A:H). The attacker can:

• Modify DNS settings to redirect traffic to attacker-controlled servers (enabling credential harvesting or MITM attacks).
• Disable firewall rules to expose internal hosts to the internet.
• Enable remote administration (e.g., open telnet/SSH services) for persistent access.
• Intercept, log, or redirect all LAN traffic passing through the device.
• Use the router as a pivot point to attack other devices on the internal network that are otherwise not reachable directly.
• Brick the device (denial of service) by applying invalid configuration or flashing corrupt firmware.

No evidence of specific threat actor campaigns using this CVE has been identified in publicly available threat intelligence at the time of writing. The exploit is publicly available, which significantly lowers the barrier to entry for opportunistic attackers.

Impact Assessment

Business Impact: The Tenda AC1206 is a consumer-grade SOHO (Small Office/Home Office) wireless router. For enterprise environments, these devices are most commonly found in branch offices, remote workers' home networks, small retail locations, or as temporary network infrastructure. A compromise of such a device can have cascading effects:

• Confidentiality breach: All unencrypted LAN traffic passing through the router can be captured. This may include internal credentials, business communications, or customer data.
• Integrity breach: The attacker can modify firewall rules, DNS settings, or routing tables. DNS poisoning attacks alone can redirect users to phishing sites impersonating corporate portals, leading to credential theft.
• Availability breach: The router can be rendered inoperable, disconnecting the LAN from the internet, causing operational downtime.
• Pivot point: The compromised router becomes a gateway into the otherwise protected internal network. Attackers can use it to scan for and exploit internal hosts that are not directly internet-exposed.

CVSS Subscore Analysis:

• Attack Vector: Network (AV:N) — remotely exploitable over the internet.
• Attack Complexity: Low (AC:L) — no special conditions required.
• Privileges Required: None (PR:N) — no account needed.
• User Interaction: None (UI:N) — victim does nothing.
• Scope: Changed (S:C) — impact extends beyond the device to the network it serves.
• Confidentiality/Integrity/Availability: High/High/High — full compromise of the device and its traffic.

Blast Radius: Every Tenda AC1206 running firmware 15.03.06.23 that is accessible over the network is vulnerable. This includes devices with the web UI exposed to the internet (via port forwarding or UPnP) and devices reachable from an internal network where an attacker already has a foothold. Given the public exploit availability, the expected time-to-exploit after a router appears in scan results is extremely short (hours, possibly minutes).

Detection Guidance

Detection of this attack is challenging because the vulnerability is an authentication bypass — the malicious request looks like a normal HTTP request to the vulnerable endpoint but lacks authentication headers. Network-based detection should focus on traffic destined for the /goform/ate path. Host-based detection is not applicable to routers in most SIEM deployments, but syslog or SNMP traps from the router may reveal configuration changes or reboots post-exploitation.

Sigma Rule

The following Sigma rule detects HTTP requests to the vulnerable endpoint without authentication cookies. It is designed for deployment on web proxies, next-generation firewalls, or HTTP access logs ingested into a SIEM.

title: Tenda AC1206 Authentication Bypass Attempt (CVE-2026-82694)
id: 3f7a3c2e-1a4b-4d5e-8f9a-2b3c4d5e6f7a
status: experimental
description: Detects HTTP requests targeting the /goform/ate endpoint on Tenda devices without authentication indicators, indicating a potential CVE-2026-82694 exploitation attempt.
author: ValtersIT Threat Intelligence
date: 2026/06/15
logsource:
  category: webserver
  product: generic
detection:
  selection:
    cs-uri-path|contains: '/goform/ate'
    cs-method:
      - 'GET'
      - 'POST'
  filter_authenticated:
    cs-cookie|contains: 'Admin'
  condition: selection and not filter_authenticated
level: high
falsepositives:
  - Legitimate router maintenance activities performed by IT staff via the diagnostic interface
  - Factory reset or diagnostic operations performed locally by an admin
fields:
  - src_ip
  - dst_ip
  - cs-uri-path
  - cs-user-agent
tags:
  - attack.initial-access
  - attack.t1190
  - cve.2026-82694
  - cwe.287

YARA Rule

The following YARA rule targets HTTP-based exploit payloads or network traffic captures (PCAP files) containing the vulnerable endpoint string. It is designed for threat hunting across packet captures and HTTP proxy logs.

rule Tenda_AC1206_Auth_Bypass_CVE_2026_82694 {
    meta:
        author = "ValtersIT Threat Intelligence"
        description = "Detects HTTP traffic referencing the vulnerable /goform/ate endpoint on Tenda AC1206 devices"
        date = "2026-06-15"
        cve = "CVE-2026-82694"
        cwe = "CWE-287"
        severity = "critical"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-82694"
    strings:
        $s1 = "/goform/ate" ascii wide nocase
        $s2 = "R7WebsSecurityHandler" ascii wide nocase
        $s3 = "Tenda" ascii wide nocase
    condition:
        uint16(0) == 0x4d3c or
        uint32(0) == 0x0a0d0a0d or
        filesize < 10MB
        and any of ($s1, $s2) and $s3
}

Suricata IDS Rule

The following Suricata rule detects unauthenticated HTTP requests to the /goform/ate endpoint. It triggers when no Cookie header is present in the request, indicating a lack of authenticated session.

alert http any any -> any any (msg:"CVE-2026-82694 Tenda AC1206 Authentication Bypass Attempt"; flow:to_server,established; http.uri; content:"/goform/ate"; http.method; content:"GET"; offset:0; nocase; http.request_line; pcre:"/^(GET|POST) \/goform\/ate/"; http.header_names; content:"!Cookie"; nocase; classtype:attempted-admin; sid:2026082694; rev:1; reference:cve,2026-82694; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-82694;)

Elastic Detection

The following Elastic EQL query detects HTTP requests to the vulnerable endpoint in Elasticsearch indices containing web server or proxy logs.

sequence by source.ip, destination.ip
  [ network where network.protocol == "http"
      and http.request.method in ("GET", "POST")
      and url.path == "/goform/ate" ]
  [ network where network.protocol == "http"
      and not http.request.headers.cookie like "*Admin*" ]

Splunk SPL Query

The following Splunk query ingests web proxy or firewall logs and searches for requests targeting the vulnerable endpoint.

index=web sourcetype=access_combined OR sourcetype=proxylog
| where like(uri_path, "%/goform/ate%")
| where NOT (like(cookie, "%Admin%") OR like(cookie, "%session%") OR like(cookie, "%authenticated%"))
| stats count by src_ip, dest_ip, uri_path, http_method, status
| sort - count
| table src_ip, dest_ip, uri_path, http_method, status, count

Wazuh OSSEC Rule

The following Wazuh XML rule detects HTTP requests to the vulnerable endpoint in Apache or Nginx access logs shipped to the Wazuh manager.

<group name="tenda,">
  <rule id="100294" level="12">
    <decodedate>%Y-%m-%dT%H:%M:%S</decodedate>
    <field name="url" type="pcre2">/goform/ate</field>
    <field name="method" type="pcre2">GET|POST</field>
    <description>Tenda AC1206 authentication bypass attempt detected (CVE-2026-82694)</description>
    <mitre>
      <id>T1190</id>
    </mitre>
    <group>authentication_bypass,tenda_router,web_attack,</group>
    <info type="cve">2026-82694</info>
    <info type="cwe">287</info>
  </rule>
</group>

Mitigation & Patch Guidance

Patch Confidence: 0/4 — UNPATCHED. No patch evidence exists from any tracked source. The vendor (Tenda) has not released a firmware update addressing this vulnerability, and no workarounds are officially documented.

Immediate Mitigations (no vendor fix available):

1. Restrict network access: If the router's web interface does not need to be publicly accessible, block inbound access to TCP port 80 (HTTP) and TCP port 443 (HTTPS) on any upstream firewall. Disable remote management features on the router itself if the device allows it to be disabled.
2. Utilize the router's host-based firewall: If the router supports access control lists for management interfaces, configure it to accept web management traffic only from trusted internal IP addresses.
3. Isolate the device: Place the router behind a dedicated firewall that enforces strict egress filtering and blocks unsolicited inbound connections to the management interface.
4. Monitor and alert: Deploy the detection rules listed above (Sigma, Suricata) on any network security device that can observe traffic to the router. Ensure logs are retained for forensic analysis.
5. Disable unused interfaces: If the /goform/ate endpoint is only for factory diagnostics and no legitimate maintenance requires it, consider blocking access to this specific path via a web application firewall (WAF) or reverse proxy if one sits in front of the router (uncommon for SOHO devices).
6. VLAN segmentation: Isolate the router and its local network segment from the rest of the corporate network to contain lateral movement in the event of compromise.

Patch/Upgrade Steps:

• Monitor the Tenda official website (tenda.com.cn and tenda.com) and firmware release notes for any updates for the AC1206 model.
• Subscribe to NVD email alerts and ValtersIT threat intel feeds for CVE-2026-82694 to be notified when a patch becomes available.
• When a patch is released, download the firmware from the official vendor site (do not trust third-party downloads), verify the checksum, and apply it through the router's web interface or TFTP recovery mode.
• After applying a patch, factory reset the device and reconfigure it from scratch to clear any post-exploitation persistence mechanisms.

Long-Term Hardening:

• Replace end-of-life equipment: If the AC1206 does not receive a timely patch, plan to replace it with a vendor that has a demonstrated track record of releasing security updates in a timely fashion.
• Disable remote management: Ensure UPnP is disabled (it often enables remote management automatically) and never expose the router management interface to the internet.
• Change default credentials: If the firmware is ever upgraded, immediately change the default admin credentials to a strong, unique password.
• Firmware update policy: Implement a procedure to check for firmware updates on a quarterly basis for all network infrastructure devices.
• Network segmentation: Never put SOHO routers on the same flat network as corporate assets. Use dedicated VLANs and enforce role-based access.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2026-82694 — Official NVD record containing the CVSS vector, CWE classification, and description.
2. Tenda Official Website: https://www.tenda.com.cn — Vendor site for firmware updates and product advisories. No CVE-specific advisory has been published as of this writing; this link is for monitoring.
3. CISA Known Exploited Vulnerabilities Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog — CVE-2026-82694 is NOT listed on the CISA KEV catalog as of this writing, indicating no official confirmation of in-the-wild exploitation by CISA.
4. Exploit-DB (Public Exploit Repository): https://www.exploit-db.com — The NVD description states the exploit is publicly available; search terms "Tenda AC1206" or "CVE-2026-82694" may return the public PoC.
5. FIRST.org EPSS Feed: https://www.first.org/epss — The EPSS score for this CVE has not yet been published; this link will provide the scoring when available.

Threat Actor Campaigns: No specific threat actor campaigns have been publicly attributed to CVE-2026-82694 at the time of this report. However, Tenda devices have been historically targeted by botnet operators (e.g., Mirai variants) and IoT-focused malware families. The public exploit availability and critical CVSS score make inclusion in automated IoT botnet scanning and infection scripts highly likely in the near term. Organizations are advised to treat any affected device as actively at risk.