In TightVNC 1.3.10, there is an integer signedness error and resultant heap-based buffer overflow in InitialiseRFBConnection in rfbproto.c (for the vncviewer component). There is no check on the size given to malloc, e.g., -1 is accepted. This allocates a chunk of size zero, which will give a heap pointer. However, one can send 0xffffffff bytes of data, which can have a DoS impact or lead to remote code execution.

References

• https://nvd.nist.gov/vuln/detail/CVE-2022-23967
• https://github.com/MaherAzzouzi/CVE-2022-23967
• https://www.tightvnc.com/licensing-server-x11.php