NuytsTech Security

CVE-2026-43011

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

net/x25: Fix potential double free of skb

When alloc_skb fails in x25_queue_rx_frame it calls kfree_skb(skb) at
line 48 and returns 1 (error).
This error propagates back through the call chain:

x25_queue_rx_frame returns 1
|
v
x25_state3_machine receives the return value 1 and takes the else
branch at line 278, setting queued=0 and returning 0
|
v
x25_process_rx_frame returns queued=0
|
v
x25_backlog_rcv at line 452 sees queued=0 and calls kfree_skb(skb)
again

This would free the same skb twice. Looking at x25_backlog_rcv:

net/x25/x25_in.c:x25_backlog_rcv() {
…
queued = x25_process_rx_frame(sk, skb);
…
if (!queued)
kfree_skb(skb);
}

More information : https://git.kernel.org/stable/c/143d4fa68ae9efb83b0c55b12cc7f0d03732a2b1

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