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The vulnerability in CVE-2026-49201 stems from a rudimentary cryptographic implementation failure: the `upload.cgi` binary, which manages the device’s backup operations, contains a statically embedded, AES-encryption key (CWE-798). This key is identical across all affected devices, turning a security control into a static secret.
An attacker with network access to the device can first capture a legitimate system backup file, as these are often accessible or can be generated by an authenticated user. Using the widely known, hardcoded AES key extracted from the firmware (e.g., via reverse engineering the `upload.cgi` binary), the attacker can then decrypt the entire backup archive. This decryption reveals the router’s complete configuration, including sensitive data like user credentials, firewall rules, VPN settings, and other internal parameters.
Once the backup is decrypted and its contents fully understood, the attacker can modify any part of the configuration, typically injecting a malicious script or altering a binary to create a persistent backdoor. This injection could be achieved by adding a new cron job, replacing a legitimate system binary with a trojanized version, or creating a new, hidden administrative user. After the malicious modifications are made, the attacker re-encrypts the backup archive using the same, known, hardcoded AES key, ensuring the file structure and headers remain intact to avoid detection by the router.
Finally, the attacker uses the device’s standard firmware restoration mechanism to upload the modified, re-encrypted backup file. Because the router trusts the integrity of any backup encrypted with its internal key, it accepts the file without any signature validation. Upon restoration, the router loads the attacker’s injected components. This creates a persistent backdoor that survives factory resets and firmware updates (if the backup mechanism is re-used), granting the attacker long-term, stealthy access and full control over the device and its network traffic.
DailyCVE Form:
Platform: Acer Wave7
Version: T7c_GBL_1.01.000055
Vulnerability : Hardcoded AES Key
Severity: 10.0 Critical
date: 2026-05-29
Prediction: By June 2026
What Undercode Say:
Analytics on this CVE show a CVSS 4.0 score of 10.0, indicating a critical vulnerability that is network exploitable with low attack complexity. The CWE-798 weakness is found in the `upload.cgi` binary of firmware version `T7c_GBL_1.01.000055` or earlier. Use the following bash commands to analyze or simulate the issue:
Extract the hardcoded AES key from the firmware (simulated) binwalk -e Wave7_Firmware.bin strings squashfs-root/usr/bin/upload.cgi | grep -i "aes_key" Decrypt a captured backup 'config.bak' (if key is known) openssl enc -d -aes-256-cbc -in config.bak -out decrypted_config.tar -K 4C4A6F4B57694C6C656B6579 -iv 0 Modify the extracted config (e.g., inject backdoor) echo "nc -lvp 4444 -e /bin/sh" >> decrypted_config/etc/init.d/backdoor.sh Re-encrypt the modified backup for upload openssl enc -e -aes-256-cbc -in decrypted_config.tar -out malicious.bak -K 4C4A6F4B57694C6C656B6579 -iv 0
How Exploit:
Exploitation does not require authentication. An attacker can perform a “backup modification attack” by extracting the key from the binary, decrypting a backup, injecting a reverse shell into a startup script, and restoring the malicious backup via upload.cgi.
Protection:
Until a patch is released, disable remote management (WAN-side admin access) or restrict access to trusted IP addresses. Post-patch, all devices must be upgraded to a version that removes the hardcoded key and implements secure key management.
Impact:
Successful exploitation leads to a full device compromise and persistent backdoor access, allowing an attacker to decrypt backups, steal credentials, monitor network traffic, and pivot into internal networks with root privileges.
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Sources:
Reported By: nvd.nist.gov
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