CVE-2026-53220

Summary

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

netfilter: revalidate bridge ports

ebt_redirect_tg() dereferences br_port_get_rcu() return without a NULL check, causing a kernel panic when the bridge port has been removed between the original hook invocation and an NFQUEUE reinject.

A mere NULL check isn't sufficient, however. As sashiko review points out userspace can not only remove the port from the bridge, it could also place the device in a different virtual device, e.g. macvlan.

If this happens, we must drop the packet, there is no way for us to reinject it into the bridge path.

Switch to _upper API, we don't need the bridge port structure. Also, this fix keeps another bug intact:

Both nfnetlink_log and nfnetlink_queue use CONFIG_BRIDGE_NETFILTER too aggressive, which prevents certain logging features when queueing in bridge family: NETFILTER_FAMILY_BRIDGE can be enabled while the old CONFIG_BRIDGE_NETFILTER cruft is off.

Fixes tag is a common ancestor, this was always broken.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/43330a1e8aace6b5a8de9aba127e9e394ab49b0f
• https://git.kernel.org/stable/c/4beffcd726e2a731cea4dc18e1fbc55c8d76f1a0
• https://git.kernel.org/stable/c/d4b1301fd3c9e5e105fd3767c68bc4ba558bb228
• https://git.kernel.org/stable/c/ccb9fd4b87538ccf19ccff78ee26700526d94867

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