Bug 2492740 (CVE-2026-53220)

Summary: CVE-2026-53220 kernel: netfilter: revalidate bridge ports
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's netfilter component. A local attacker could exploit a NULL pointer dereference vulnerability in the `ebt_redirect_tg()` function. This occurs when a bridge port is removed and a packet is reinjected into NFQUEUE, leading to a kernel panic and a Denial of Service (DoS) for the system.
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Description OSIDB Bzimport 2026-06-25 10:03:15 UTC 
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.
Comment 1 Keith Grant 2026-06-25 22:33:14 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062505-CVE-2026-53220-807b@gregkh/T