CVE-2026-74255

About vulnerability

In the Linux kernel, the following vulnerability has been resolved:

tipc: fix UAF in tipc_l2_send_msg()

Syzbot reported a slab-use-after-free in ipvlan_hard_header() when called from tipc_l2_send_msg().

The root cause is that tipc_disable_l2_media() calls synchronize_net() while b->media_ptr is still valid. This allows concurrent RCU readers to obtain the device pointer after synchronize_net() has finished. The pointer is cleared later in bearer_disable(), but without any subsequent synchronization, allowing the device to be freed while still in use by readers.

Fix this by clearing b->media_ptr in tipc_disable_l2_media() before calling synchronize_net().

This is safe to do now because the call order in bearer_disable() was reversed in 0d051bf93c06 (“tipc: make bearer packet filtering generic”) to call tipc_node_delete_links() (which needs the pointer) before disable_media().

https: //lore.kernel.org/netdev/[email protected]/T/#u

Affected product:

Debian 10 ELS , Debian 11 ELS , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS

Affected packages:

linux @ 4.19.0 (+4 more)

Live-patch status from KernelCare for each operating system.