CVE-2026-63836

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description A divide-by-zero error exists in the batman-adv module within the batadv tp update cwnd() function. The issue occurs during the calculation of dec cwnd when the cwnd variable reaches the value 0x20000000. Due to the use of unsigned 32-bit arithmetic, shifting cwnd by 3 bits to the left causes an integer overflow, resulting in a value of 0. This leads to a division by zero when the system attempts to calculate ((mss * 8) ** 2) / (cwnd * 8). To prevent this, the calculation is simplified to (mss ** 2) * 8 / cwnd to avoid the overflow in the divisor while maintaining precision.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.