CVE-2026-97964

Summary

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux4cf476ced45d7f12df30a68e833b263e7a2202d1 < 3af7797fbabc84992e0ca5ad2bc0ca8537d053efaffected
LinuxLinux4cf476ced45d7f12df30a68e833b263e7a2202d1 < 0996c3e6bcc6ae08cb371ed43648c9f7f748ae6eaffected
LinuxLinux4cf476ced45d7f12df30a68e833b263e7a2202d1 < 15d0a6c9a42df2d745c37510dba828f6dbe60d9faffected
LinuxLinux4cf476ced45d7f12df30a68e833b263e7a2202d1 < 8aaeb56aff2a557a88f83ae866da2c91ad247e59affected
LinuxLinux5.11affected
LinuxLinux0 < 5.11unaffected
LinuxLinux6.12.111 <= 6.12.*unaffected
LinuxLinux6.18.53 <= 6.18.*unaffected
LinuxLinux7.2.7 <= 7.2.*unaffected
LinuxLinux7.3-rc3 <= *unaffected

Weaknesses

References