CVE-2026-64177

Technical Description

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

phonet/pep: disable BH around forwarded sk_receive_skb()

The networking receive path is usually run from softirq context, but

protocols that take the socket lock may have packets stored in the

backlog and processed later from process context. In that case

release_sock() -> __release_sock() drops the slock with spin_unlock_bh()

and then calls sk->sk_backlog_rcv() with bottom halves enabled.

Typical sk_backlog_rcv handlers process the socket whose backlog is

being drained, so the BH state at entry is irrelevant for the slocks

they touch. pep_do_rcv() is different: when the inbound skb targets an

existing PEP pipe, it forwards the skb to a different *child* socket

via sk_receive_skb(). That helper takes the child slock with

bh_lock_sock_nested(), which is just spin_lock_nested() and assumes BH

is already off. The same child slock therefore ends up acquired with

BH on (process path) and with BH off (softirq path):

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Remediation

Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected Products

References