CVE-2026-7257: Zyxel WRE6505 Information Disclosure Flaw

CVE-2026-7257 Overview

CVE-2026-7257 is an insecure storage of sensitive information vulnerability affecting the Zyxel WRE6505 v2 wireless range extender running firmware version V1.00(ABDV.3)C0. The configuration file stores sensitive data in a recoverable format, allowing a local attacker with administrator privileges to download and decrypt the backup configuration file. The affected device is marked UNSUPPORTED WHEN ASSIGNED, meaning Zyxel has reached the end-of-life milestone for this hardware and will not issue a security patch. The weakness is classified under CWE-922: Insecure Storage of Sensitive Information.

Critical Impact

An authenticated local administrator can extract and decrypt the device backup configuration file, exposing stored credentials and network secrets that could be reused to pivot into adjacent networks.

Affected Products

• Zyxel WRE6505 v2 hardware (end-of-life)
• Zyxel WRE6505 firmware version V1.00(ABDV.3)C0
• Any deployment still operating the WRE6505 v2 range extender past its support window

Discovery Timeline

• 2026-05-12 - CVE-2026-7257 published to the National Vulnerability Database
• 2026-05-16 - Last updated in NVD database

Technical Details for CVE-2026-7257

Vulnerability Analysis

The Zyxel WRE6505 v2 allows administrators to export a backup of the device configuration through the web management interface. The exported configuration file contains sensitive parameters such as administrator credentials, wireless pre-shared keys, and upstream authentication settings. The vulnerability arises because the storage and encoding scheme protecting the configuration file is reversible by an attacker who obtains the file.

An attacker who already holds administrator privileges, whether through legitimate credentials, credential reuse, or a prior compromise, can download the backup and decrypt its contents offline. Because the device is no longer supported, no firmware update will close this gap. Exposure is constrained to local access scenarios, as reflected by the attack vector classification. The recovered secrets can then be used to attack the parent wireless network or systems where the same credentials have been reused.

Root Cause

The root cause is the use of a weak or predictable protection mechanism for configuration data at rest. Sensitive fields are obfuscated rather than protected by a robust, key-managed encryption scheme tied to a secret the attacker cannot recover from the device. This pattern maps directly to CWE-922.

Attack Vector

Exploitation requires local access and administrator privileges on the device. The attacker authenticates to the management interface, downloads the backup configuration file, and runs the file through a decryption routine that reverses the device's storage encoding. Successful exploitation yields plaintext credentials and configuration secrets. Confidentiality is impacted; integrity and availability are not directly affected. No public proof-of-concept code or exploit module has been published.

No verified exploit code is available. Refer to the Zyxel End of Life Notice for the vendor support position.

Detection Methods for CVE-2026-7257

Indicators of Compromise

• Unexpected downloads of the backup configuration file from the WRE6505 v2 administrative interface
• Administrator session logins from unusual local hosts or at unexpected times
• Presence of WRE6505 backup files (typically with a .rom or .cfg extension) on workstations not used for network administration

Detection Strategies

• Monitor management plane traffic to the device and alert on HTTP requests that retrieve the configuration backup endpoint
• Track administrator authentication events and correlate them with configuration export activity to surface anomalies
• Inventory legacy network hardware and flag any WRE6505 v2 devices running firmware V1.00(ABDV.3)C0 for accelerated replacement

Monitoring Recommendations

• Forward syslog or SNMP traps from the WRE6505 v2 to a centralized logging platform for retention and correlation
• Audit which user accounts hold administrator rights on the device and review the audit trail on a recurring schedule
• Alert on lateral reuse of credentials extracted from configuration backups, particularly Wi-Fi pre-shared keys appearing on new clients

How to Mitigate CVE-2026-7257

Immediate Actions Required

• Replace the Zyxel WRE6505 v2 with a vendor-supported device, since the hardware is end-of-life and will not receive a patch
• Rotate all credentials and pre-shared keys that were ever stored in the device configuration
• Restrict management interface access to a dedicated administrative VLAN or host until the device is decommissioned
• Remove or disable any unused administrator accounts on the device

Patch Information

No patch is available. The device is marked UNSUPPORTED WHEN ASSIGNED by Zyxel. Consult the Zyxel End of Life Notice for confirmation of the support status and migration guidance.

Workarounds

• Place the WRE6505 v2 on an isolated network segment with no route to sensitive systems
• Enforce strong, unique administrator credentials that are not reused on any other system or device
• Disable remote management features and restrict access to physically trusted local hosts only
• Plan and execute a hardware refresh to a supported wireless extender as the durable remediation

# Configuration example: isolate the legacy extender on a dedicated VLAN
# (Cisco IOS style, adapt to your switch platform)
vlan 99
 name LEGACY-WRE6505-QUARANTINE
interface GigabitEthernet0/10
 description WRE6505 v2 (EOL - CVE-2026-7257)
 switchport mode access
 switchport access vlan 99
 spanning-tree portfast
!
ip access-list extended QUARANTINE-WRE6505
 permit tcp 10.10.99.0 0.0.0.255 host 10.10.99.1 eq 443
 deny ip 10.10.99.0 0.0.0.255 any