CVE-2026-19412: CP Plus Router Authentication Bypass Flaw

CVE-2026-19412 Overview

CVE-2026-19412 is a hardcoded credentials vulnerability [CWE-798] affecting the CP Plus CP-XR-DE21-S Router. The firmware embeds HTTP Digest authentication credentials that are identical across every device running the affected build. An attacker on the adjacent network can extract these credentials from the firmware and authenticate to the device's web management interface. Successful exploitation grants unauthorized administrative access and enables privileged operations on the router.

Critical Impact
Attackers on the local network can recover static credentials from firmware to gain full administrative control over affected CP Plus routers, compromising confidentiality, integrity, and availability of the device.

Affected Products

CP Plus CP-XR-DE21-S Router
Firmware versions containing the hardcoded HTTP Digest credentials (see CERT-In Vulnerability Note CIVN-2026-0428)

Discovery Timeline

2026-08-28 - CVE-2026-19412 published to NVD
2026-09-01 - Last updated in NVD database

Technical Details for CVE-2026-19412

Vulnerability Analysis

The CP-XR-DE21-S router firmware ships with static HTTP Digest authentication credentials baked into the image. Because the same credentials exist on every device running the affected firmware, recovery on one unit yields access to all deployed units. HTTP Digest authentication is used by the router's web management interface to gate administrative actions. Once an attacker replays the hardcoded credentials, the server treats the session as an authenticated administrator.

The attack does not require prior user interaction or elevated privileges. An adjacent-network position, such as a connected LAN or Wi-Fi segment, is the only prerequisite. The vulnerability class is tracked as Use of Hard-coded Credentials [CWE-798].

Root Cause

The firmware developers embedded fixed authentication material rather than provisioning per-device credentials during manufacturing or first-boot setup. This design choice removes the isolation normally provided by unique secrets. Anyone who obtains the firmware image, whether through vendor downloads, physical extraction from a flash chip, or a firmware update capture, can recover the credential material through static analysis.

Attack Vector

An attacker on the same broadcast domain or routed adjacent network locates the router's administrative HTTP interface. The attacker supplies the hardcoded username and password recovered from firmware analysis to satisfy the HTTP Digest challenge. The router accepts the response and grants an administrative session. From there, the attacker can modify routing rules, alter DNS settings, enable remote management, exfiltrate configuration, or pivot deeper into the network.

No verified proof-of-concept code is publicly available. Refer to the CERT-In Vulnerability Note CIVN-2026-0428 for the authoritative advisory.

Detection Methods for CVE-2026-19412

Indicators of Compromise

Successful HTTP Digest authentications to the router's management interface from unexpected internal hosts or previously unseen MAC addresses.
Unauthorized configuration changes, including modified DNS servers, new port-forwarding rules, or newly enabled remote management services.
Firmware or configuration exports initiated outside scheduled administrative windows.

Detection Strategies

Inspect router logs for administrative logins that do not correlate with authorized change tickets.
Baseline the router configuration and alert on any drift from the approved state.
Monitor for connections to the router's administrative port (typically TCP/80 or TCP/443) from non-administrative subnets.

Monitoring Recommendations

Forward router syslog and authentication events to a centralized logging platform for correlation.
Alert on repeated Digest authentication attempts sourced from adjacent-network hosts.
Track outbound traffic from the router itself for signs of misuse following credential compromise.

How to Mitigate CVE-2026-19412

Immediate Actions Required

Restrict access to the router's administrative interface to a dedicated management VLAN or a small allowlist of administrator hosts.
Disable remote (WAN-side) management on affected CP-XR-DE21-S devices until a patched firmware is applied.
Segment untrusted users, guest Wi-Fi, and IoT endpoints away from the router's management network.
Audit router configuration for unauthorized changes and reset the device to a known-good configuration if tampering is suspected.

Patch Information

At the time of publication, consult the CERT-In Vulnerability Note CIVN-2026-0428 for the current vendor guidance and any firmware update released by CP Plus. Apply the vendor-supplied firmware update to all affected CP-XR-DE21-S routers as soon as it is available. Because the credentials are identical across devices, patching a subset of the fleet does not reduce risk for unpatched units.

Workarounds

Place affected routers behind an upstream firewall that blocks inbound access to management ports from user and guest subnets.
Enforce network access control (NAC) so only authorized endpoints can reach the router's LAN-side management interface.
Monitor firmware update channels from CP Plus and schedule a rollout window as soon as a fix is published.