A weak encryption flaw in the firmware of the CSL 1010 M2M 3G WiFi Module allows an unauthenticated attacker to recover all stored secrets in plain text by reversing a single‑byte XOR cipher applied to the Router.cfg backup file. The static key used for obfuscation means the decryption process is trivial, exposing web administration credentials, telnet passwords, wireless pre‑shared keys, PPPoE and 3G/APN credentials, and SIM identifiers such as IMSI and IMEI. This represents a classic credential‑exposure issue caused by improper encryption, classified under CWE‑261.

Products affected include CSL Mobile Limited’s CSL 1010 M2M 3G WiFi Module with firmware version 2.2.1.4 and any earlier releases that have not been updated. Users running these firmware images are vulnerable until a remediation such as a firmware update is applied.

The likely attack vector involves accessing the Router.cfg backup file via exposed interfaces or an unauthorized remote backup retrieval, which is inferred from the description as the precise retrieval method is not explicitly stated. The CVSS v3.1 score of 6.9 indicates moderate severity, and the EPSS score of less than 1% suggests a low probability of exploitation. The vulnerability is not listed in the CISA KEV catalogue. Attackers can obtain the Router.cfg backup file through exposed interfaces or unauthorized remote backup retrieval; at that point they can trivially remove the obfuscation by applying a single‑byte XOR operation with a static key to recover the sensitive information. Because the attack does not require authentication and the decryption is straightforward, the risk to confidentiality is significant.