Valve's Game Networking Sockets prior to version v1.2.0 improperly handles long encrypted messages in function AES_GCM_DecryptContext::Decrypt() when compiled using libsodium, leading to a Stack-Based Buffer Overflow and resulting in a memory corruption and possibly even a remote code execution.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-6018
• ValveSoftware/GameNetworkingSockets@bea84e2
• https://research.checkpoint.com/2020/game-on-finding-vulnerabilities-in-valves-steam-sockets/