CVE-2026-53220
MediumCVSS 5.5Exploitation Probability (EPSS)
Low risk3th percentile — higher than 3% of all known CVEs
Summary
In the Linux kernel, a vulnerability was found in netfilter where ebt_redirect_tg() dereferences br_port_get_rcu() return without NULL check, causing kernel panic when the bridge port is removed between hook invocation and NFQUEUE reinject. Userspace could also move the device to a different virtual interface, requiring packet drop.
Risk Assessment
An attacker with user privileges can cause a kernel panic by removing a bridge port or changing its configuration during packet processing, leading to denial of service (DoS).
Recommendation
Immediately update the Linux kernel to a version containing the fix that replaces br_port_get_rcu() with the _upper API and adds proper checks.
Original NVD description (English source)
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.