CVE-2026-1740 Overview
CVE-2026-1740 is an authentication bypass vulnerability affecting EFM ipTIME A8004T routers running firmware version 14.18.2. The flaw resides in the httpcon_check_session_url function within /cgi/timepro.cgi, part of the Hidden Hiddenloginsetup Interface. Improper authentication handling [CWE-287] allows remote attackers to manipulate session validation logic. The exploit has been publicly disclosed, and the vendor did not respond to early disclosure attempts. This vulnerability impacts the confidentiality, integrity, and availability of the router's administrative interface at a limited scope.
Critical Impact
Remote attackers can bypass authentication on affected ipTIME A8004T routers without credentials, potentially exposing router configuration and network management functions.
Affected Products
- EFM ipTIME A8004T router (hardware)
- ipTIME A8004T firmware version 14.18.2
- Deployments exposing the web management interface (/cgi/timepro.cgi) to untrusted networks
Discovery Timeline
- 2026-02-02 - CVE-2026-1740 published to NVD
- 2026-04-29 - Last updated in NVD database
Technical Details for CVE-2026-1740
Vulnerability Analysis
The vulnerability exists in the httpcon_check_session_url function in /cgi/timepro.cgi, which is responsible for validating session state for requests routed through the Hidden Hiddenloginsetup Interface. The function performs improper authentication checks, allowing attacker-controlled input to bypass session validation. An attacker reaching the web interface over the network can manipulate request parameters to access protected functionality without valid credentials. The exploit has been made public, increasing the likelihood of opportunistic attacks against exposed devices. The vendor did not respond to disclosure attempts, and no official patch has been published at the time of NVD publication.
Root Cause
The root cause is improper authentication logic [CWE-287] within the httpcon_check_session_url routine. The function fails to enforce a complete session check before processing requests to the hidden login setup interface. This trust gap allows unauthenticated requests to reach handlers that should require authenticated sessions. The presence of a "hidden" administrative interface compounds the risk by exposing privileged endpoints not visible to legitimate users.
Attack Vector
The attack vector is network-based and requires no privileges or user interaction. An attacker sends crafted HTTP requests to the /cgi/timepro.cgi endpoint targeting the Hidden Hiddenloginsetup Interface. Routers exposing their web management interface to the WAN or to untrusted LAN segments are at greatest risk. Because the exploit details are public, attackers can incorporate this technique into automated scanning and exploitation toolkits.
No verified proof-of-concept code is available for inclusion. Technical details on the request structure and the affected handler are referenced in the GitHub CVE Issue Discussion and the VulDB entry for ID 343639.
Detection Methods for CVE-2026-1740
Indicators of Compromise
- Unauthenticated HTTP requests targeting /cgi/timepro.cgi with parameters referencing hiddenloginsetup or related session paths
- Unexpected configuration changes on ipTIME A8004T routers, including DNS server, firewall rule, or admin credential modifications
- New or unfamiliar administrative sessions originating from external IP addresses in router logs
Detection Strategies
- Inspect router access logs for repeated requests to /cgi/timepro.cgi from unfamiliar source addresses
- Deploy network intrusion detection signatures for HTTP requests containing httpcon_check_session_url bypass patterns or hiddenloginsetup references
- Monitor egress traffic from the router for indicators of compromise such as connections to known command-and-control infrastructure
Monitoring Recommendations
- Forward router syslog data to a centralized logging platform for correlation with broader network telemetry
- Alert on configuration changes to ipTIME A8004T devices outside of approved change windows
- Track authentication events on the management interface and flag successful sessions that lack a preceding valid login
How to Mitigate CVE-2026-1740
Immediate Actions Required
- Disable remote WAN-side administration on affected ipTIME A8004T routers immediately
- Restrict access to the web management interface to a dedicated management VLAN or specific trusted IP addresses
- Rotate administrator credentials and audit existing configuration for unauthorized modifications
- Inventory deployed ipTIME A8004T devices running firmware 14.18.2 and prioritize them for isolation or replacement
Patch Information
No vendor patch is available at the time of publication. The vendor was contacted prior to public disclosure but did not respond. Administrators should monitor the ipTIME firmware download portal for future firmware updates addressing the httpcon_check_session_url flaw and apply them as soon as released.
Workarounds
- Block external access to TCP ports used by the router's web management interface at the network perimeter
- Place affected routers behind a separate firewall enforcing strict access control to management endpoints
- Where feasible, replace affected devices with hardware from a vendor that maintains an active security response process
# Example: restrict management interface access to a trusted subnet
# (apply on upstream firewall, not the vulnerable router itself)
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -s 192.168.10.0/24 -j ACCEPT
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -s 192.168.10.0/24 -j ACCEPT
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
