CVE-2026-23359 in Linux Kernel

Summary

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

bpf: Fix stack-out-of-bounds write in devmap

get_upper_ifindexes() iterates over all upper devices and writes their
indices into an array without checking bounds.

Also the callers assume that the max number of upper devices is
MAX_NEST_DEV and allocate excluded_devices[1+MAX_NEST_DEV] on the stack,
but that assumption is not correct and the number of upper devices could
be larger than MAX_NEST_DEV (e.g., many macvlans), causing a
stack-out-of-bounds write.

Add a max parameter to get_upper_ifindexes() to avoid the issue.
When there are too many upper devices, return -EOVERFLOW and abort the
redirect.

To reproduce, create more than MAX_NEST_DEV(8) macvlans on a device with
an XDP program attached using BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS.
Then send a packet to the device to trigger the XDP redirect path.

Responsible

Linux

Reservation

01/13/2026

Disclosure

03/25/2026

Entries

VulDB provides additional information and datapoints for this CVE:

ID	Vulnerability	CWE	Exp	Cou	CVE
353093	Linux Kernel get_upper_ifindexes out-of-bounds write	787	Not defined	Official fix	CVE-2026-23359