CVE Catalog

CVE-2026-72255

HighCVSS 7.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.16%

6th percentile - higher than 6% of all known CVEs

Summary

In the Linux kernel, an issue was found in netfilter nf_queue regarding pinning the bridge device while NFQUEUE holds a fake dst. The br_netfilter fake rtable is embedded in struct net_bridge and attached to bridged packets with skb_dst_set_noref(). If such a packet is queued to NFQUEUE, __nf_queue() upgrades that fake dst with skb_dst_force(). The fix keeps the bridge fake dst model unchanged and pins the bridge master device only while the packet sits in NFQUEUE, recording the bridge device in nf_queue_entry and taking a device reference for the queue lifetime.

Risk Assessment

The issue can lead to use-after-free or system crash during bridge teardown, potentially affecting network stability.

Recommendation

It is recommended to update the Linux kernel to a version containing the fix that pins the bridge device while queuing to NFQUEUE.

Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_queue: pin bridge device while NFQUEUE holds fake dst The br_netfilter fake rtable is embedded in struct net_bridge and is attached to bridged packets with skb_dst_set_noref(). If such a packet is queued to NFQUEUE, __nf_queue() upgrades that fake dst with skb_dst_force(). At that point the queued skb can hold a real dst reference after bridge teardown has started. The problem is not that every bridged packet needs its own dst reference. The problem is that NFQUEUE can keep the bridge private fake dst alive after unregister begins. Fix this by keeping the bridge fake dst model unchanged and pinning the bridge master device only while the packet sits in NFQUEUE. Record the bridge device in nf_queue_entry when the queued skb carries a bridge fake dst, take a device reference for the queue lifetime, and drop it when the queue entry is freed. Also make sure queued entries are reaped when that bridge device goes down, and drop the redundant nf_bridge_info_exists() test from the fake dst detection. This keeps netdev_priv(br->dev) alive until verdict completion, so the embedded fake rtable and its metrics backing storage cannot be freed out from under dst_release(). It also avoids the constant refcount bump and avoids using ipv4-specific dst helpers for IPv6 bridge traffic.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS