CISA added three Linux kernel vulnerabilities to its Known Exploited Vulnerabilities (KEV) catalog on 18 September, citing evidence of active exploitation: CVE-2025-39682 (9.8), an improper check for unusual or exceptional conditions in the TLS receive path that could let a local authenticated user trigger memory disclosure or denial of service; CVE-2026-53266 (8.8), an out-of-bounds write in the ebtables SNAT ARP rewrite path that could allow a local attacker to cause unintended system behaviour, denial of service or local privilege escalation; and CVE-2025-39964 (7.8), a race condition permitting concurrent writes to the same AF_ALG socket, which could crash the system or corrupt cryptographic operation results.

NVD description

In the Linux kernel, the following vulnerability has been resolved: tls: fix handling of zero-length records on the rx_list Each recvmsg() call must process either - only contiguous DATA records (any number of them) - one non-DATA record If the next record has different type than what has already been processed we break out of the main processing loop. If the record has already been decrypted (which may be the case for TLS 1.3 where we don't know type until decryption) we queue the pending record to the rx_list. Next recvmsg() will pick it up from there. Queuing the skb to rx_list after zero-copy decrypt is not possible, since in that case we decrypted directly to the user space buffer, and we don't have an skb to queue (darg.skb points to the ciphertext skb for access to metadata like length). Only data records are allowed zero-copy, and we break the processing loop after each non-data record. So we should never zero-copy and then find out that the record type has changed. The corner case we missed is when the initial record comes from rx_list, and it's zero length.