CVE-2026-97964

In the Linux kernel, the following vulnerability has been resolved: ppp_synctty: ensure a writeable skb header ppp_sync_txmunge() checks headroom before prepending the address and control bytes, but does not ensure that the skb header is writable. A received skb can reach this function through PPP channel bridging without passing through ppp_start_xmit(), which calls skb_cow_head(). For example, a PPPoE frame may share its buffer with a clone queued to an AF_PACKET socket. If it is bridged to a synchronous tty channel, the address/control bytes can overwrite data still visible to that socket. Use skb_cow_head() to ensure both sufficient headroom and a writable header.

• https://git.kernel.org/stable/c/0996c3e6bcc6ae08cb371ed43648c9f7f748ae6e
• https://git.kernel.org/stable/c/15d0a6c9a42df2d745c37510dba828f6dbe60d9f
• https://git.kernel.org/stable/c/3af7797fbabc84992e0ca5ad2bc0ca8537d053ef
• https://git.kernel.org/stable/c/8aaeb56aff2a557a88f83ae866da2c91ad247e59