CVE-2025-39946

CVE-2025-39946 refers to a vulnerability in the Linux kernel. Specifically, it addresses an issue within the Transport Layer Security (TLS) subsystem related to the handling of potentially invalid headers. The vulnerability arises because the kernel might not properly abort a stream when it belatedly discovers that a record is invalid. The flaw is triggered within the `tls_rx_msg_size()` function in `net/tls/tls_sw.c`, where an out-of-bounds read error can occur. This can be exploited locally to cause a denial-of-service (DoS) attack. It was discovered that by serving a header in small out-of-band sends and then filling the receive buffer with a large normal send, the allocated skb space could be overflowed.