CVE-2023-52767: Linux Kernel

Medium severity, CVSS 5.5. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: tls: fix NULL deref on tls_sw_splice_eof() with empty record syzkaller discovered that if tls_sw_splice_eof() is executed as part of sendfile() when the plaintext/ciphertext sk_msg are empty, the send path gets confused because the empty ciphertext buffer does not have enough space for the encryption overhead. This causes tls_push_record() to go on the `split = true` path (which is only supposed to be used when interacting with an attached BPF program), and then get further confused and hit the tls_merge_open_record() path, which then assumes that there must be at least one populated buffer element, leading to a NULL deref. It is possible to have empty plaintext/ciphertext buffers if we previously bailed from tls_sw_sendmsg_locked() via the tls_trim_both_msgs() path. tls_sw_push_pending_record() already handles this case correctly; let's do the same check in tls_sw_splice_eof().

Affected products

• Linux Linux Kernel: from 6.5, before 6.6.4 (fixed in 6.6.4); version 6.7 only

Published 2024-05-21. Last modified 2026-06-17.