CVE-2026-68284

Status: UPDATED  |  Advisory ID: CVE-2026-68284

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

bpf, sockmap: Fix cork use-after-free in tcp_bpf_sendmsg()

tcp_bpf_sendmsg() keeps msg_tx across sk_stream_wait_memory(), which

drops and reacquires the socket lock. Its error path tries to decide

whether msg_tx names the local temporary message by comparing it with

the current value of psock->cork.

This comparison is unsafe when two threads send on the same socket:

Thread A Thread B

msg_tx = psock->cork

sk_msg_alloc() fails

sk_stream_wait_memory()

releases the socket lock acquires the socket lock

completes the cork

psock->cork = NULL

frees the cork

reacquires the socket lock

msg_tx != psock->cork

sk_msg_free(msg_tx)

The stale cork is therefore mistaken for the local temporary message

and freed again. KASAN reported:

BUG: KASAN: slab-use-after-free in sk_msg_free+0x49/0x50

Read of size 4 at addr ffff88810c908800 by task poc/90

Call Trace:

sk_msg_free+0x49/0x50

tcp_bpf_sendmsg+0x14f5/0x1cc0

__sys_sendto+0x32c/0x3a0

__x64_sys_sendto+0xdb/0x1b0

Allocated by task 89:

__kasan_kmalloc+0x8f/0xa0

tcp_bpf_sendmsg+0x16b3/0x1cc0

Freed by task 91:

__kasan_slab_free+0x43/0x70

kfree+0x131/0x3c0

tcp_bpf_sendmsg+0xec3/0x1cc0

msg_tx can only name the stack-local tmp or the shared cork. Check for

tmp directly so a changed psock->cork cannot turn a shared message into

an apparent local one. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References