The War Thunder client transmits the authentication bearer token (auth_jwt) in the first data packet after establishing a TCP connection. The token is only compressed with LZ4 and not encrypted, allowing an attacker on the network path to capture and decompress the packet and read the JSON payload. This vulnerability permits an attacker to temporarily impersonate the affected user, granting access to game services and the display of personal data such as email and phone number. The attacker cannot modify account security settings, change passwords, bypass two‑factor authentication, or access financial information, so it does not enable a full account takeover.

All versions of the War Thunder client distributed by Gaijin Entertainment are affected. No specific version range is listed.

The vulnerability can be exploited by a passive network interceptor, requiring no special privileges or advanced attack techniques. The CVSS score is 4.8, which indicates moderate risk. The EPSS score is 0.00135, indicating a very low probability of exploitation. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog, indicating that large‑scale exploitation has not yet been observed.