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CVE-2026-72255 (GCVE-0-2026-72255)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:54 – Updated: 2026-08-23 12:47
VLAI
Title
netfilter: nf_queue: pin bridge device while NFQUEUE holds fake dst
Summary
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.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 34666d467cbf1e2e3c7bb15a63eccfb582cdd71f , < 8dc51351472825500145eed5bddfb88b2ec32008 (git)
Affected: 34666d467cbf1e2e3c7bb15a63eccfb582cdd71f , < 430521af7fe8a9c08f5a2554224a35f11f51d99e (git)
Affected: 34666d467cbf1e2e3c7bb15a63eccfb582cdd71f , < 3f03a2d225c668283110ad5f9ff159ba4591e2c7 (git)
Affected: 34666d467cbf1e2e3c7bb15a63eccfb582cdd71f , < 01ace27af47801dd7f6b839e782b62863af979cc (git)
Affected: 34666d467cbf1e2e3c7bb15a63eccfb582cdd71f , < 0ca505346c5e2905ab7b5313af801fcf38f594a8 (git)
Affected: 34666d467cbf1e2e3c7bb15a63eccfb582cdd71f , < 47b3af24de5fbed4bf2952de0f5294ef1a338a26 (git)
Affected: 34666d467cbf1e2e3c7bb15a63eccfb582cdd71f , < c9c9b37f8c5505224e8d206184df3bb668ee00cf (git)
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Linux Linux Affected: 3.18
Unaffected: 0 , < 3.18 (semver)
Unaffected: 5.15.217 , ≤ 5.15.* (semver)
Unaffected: 6.1.178 , ≤ 6.1.* (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_queue: pin bridge device while NFQUEUE holds fake dst\n\nThe br_netfilter fake rtable is embedded in struct net_bridge and is\nattached to bridged packets with skb_dst_set_noref(). If such a packet is\nqueued to NFQUEUE, __nf_queue() upgrades that fake dst with\nskb_dst_force().\n\nAt that point the queued skb can hold a real dst reference after bridge\nteardown has started. The problem is not that every bridged packet needs\nits own dst reference. The problem is that NFQUEUE can keep the bridge\nprivate fake dst alive after unregister begins.\n\nFix this by keeping the bridge fake dst model unchanged and pinning the\nbridge master device only while the packet sits in NFQUEUE. Record the\nbridge device in nf_queue_entry when the queued skb carries a bridge fake\ndst, take a device reference for the queue lifetime, and drop it when the\nqueue entry is freed.\n\nAlso make sure queued entries are reaped when that bridge device goes\ndown, and drop the redundant nf_bridge_info_exists() test from the fake\ndst detection.\n\nThis keeps netdev_priv(br-\u003edev) alive until verdict completion, so the\nembedded fake rtable and its metrics backing storage cannot be freed out\nfrom under dst_release(). It also avoids the constant refcount bump and\navoids using ipv4-specific dst helpers for IPv6 bridge traffic."
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              "value": "AV:L - The bug is reached via netfilter NFQUEUE and local bridge/rtnetlink setup (__nf_queue skb_dst_force on br_netfilter\u0027s embedded fake rtable, then bridge teardown while packets remain queued), not from unauthenticated remote input alone; kernel guidance classifies netfilter/nftables paths as Local.\nAC:L - With CAP_NET_ADMIN in a user namespace, an attacker can bind NFQUEUE, queue br_netfilter bridged packets, and delete the bridge while packets sit in the queue, deterministically hitting nfqnl_dev_drop/dst_release after struct net_bridge is freed.\nPR:L - Configuring NFQUEUE/nftables rules, loading br_netfilter, creating/deleting bridges, and binding nfnetlink queues require CAP_NET_ADMIN, obtainable by unprivileged users via user/network namespaces (unshare -Urn), not init-namespace root.\nUI:N - Exploitation requires only the attacker\u0027s own netlink, nftables, and traffic generation; no victim must mount filesystems, open files, or perform other interactive actions beyond the attacker\u0027s programmatic setup.\nS:U - Impact is kernel heap corruption in the same host security domain via freed embedded fake_rtable/metrics inside struct net_bridge; this is standard kernel UAF/privilege-escalation territory, not a VM, IOMMU, or sandbox boundary escape.\nC:H - skb_dst_force in __nf_queue holds a dst reference to fake_rtable storage embedded in struct net_bridge; after bridge unregister frees that object, dst_release operates on freed kmalloc memory\u2014a UAF that can disclose kernel memory via slab reuse.\nI:H - The dangling fake rtable/metrics pointer in queued skbs can be combined with heap grooming to obtain arbitrary kernel writes or control-flow hijack during dst_destroy/netdev_put, consistent with kernel UAF integrity guidance.\nA:H - Freeing queued NFQUEUE entries after bridge teardown dereferences freed net_bridge/fake_rtable in dst_release, causing kernel oops/panic-class faults; repeated triggering yields reliable denial of service on bridge/NFQUEUE deployments."
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    "dateReserved": "2026-08-09T03:40:39.915Z",
    "dateUpdated": "2026-08-23T12:47:09.141Z",
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The problem is that NFQUEUE can keep the bridge\\nprivate fake dst alive after unregister begins.\\n\\nFix this by keeping the bridge fake dst model unchanged and pinning the\\nbridge master device only while the packet sits in NFQUEUE. Record the\\nbridge device in nf_queue_entry when the queued skb carries a bridge fake\\ndst, take a device reference for the queue lifetime, and drop it when the\\nqueue entry is freed.\\n\\nAlso make sure queued entries are reaped when that bridge device goes\\ndown, and drop the redundant nf_bridge_info_exists() test from the fake\\ndst detection.\\n\\nThis keeps netdev_priv(br-\u003edev) alive until verdict completion, so the\\nembedded fake rtable and its metrics backing storage cannot be freed out\\nfrom under dst_release(). It also avoids the constant refcount bump and\\navoids using ipv4-specific dst helpers for IPv6 bridge traffic.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"include/net/netfilter/nf_queue.h\",\"net/netfilter/nf_queue.c\",\"net/netfilter/nfnetlink_queue.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"34666d467cbf1e2e3c7bb15a63eccfb582cdd71f\",\"lessThan\":\"8dc51351472825500145eed5bddfb88b2ec32008\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"34666d467cbf1e2e3c7bb15a63eccfb582cdd71f\",\"lessThan\":\"430521af7fe8a9c08f5a2554224a35f11f51d99e\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"34666d467cbf1e2e3c7bb15a63eccfb582cdd71f\",\"lessThan\":\"3f03a2d225c668283110ad5f9ff159ba4591e2c7\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"34666d467cbf1e2e3c7bb15a63eccfb582cdd71f\",\"lessThan\":\"01ace27af47801dd7f6b839e782b62863af979cc\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"34666d467cbf1e2e3c7bb15a63eccfb582cdd71f\",\"lessThan\":\"0ca505346c5e2905ab7b5313af801fcf38f594a8\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"34666d467cbf1e2e3c7bb15a63eccfb582cdd71f\",\"lessThan\":\"47b3af24de5fbed4bf2952de0f5294ef1a338a26\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"34666d467cbf1e2e3c7bb15a63eccfb582cdd71f\",\"lessThan\":\"c9c9b37f8c5505224e8d206184df3bb668ee00cf\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"include/net/netfilter/nf_queue.h\",\"net/netfilter/nf_queue.c\",\"net/netfilter/nfnetlink_queue.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"3.18\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"3.18\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.217\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.178\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.145\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.97\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.40\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.5\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/01ace27af47801dd7f6b839e782b62863af979cc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/0ca505346c5e2905ab7b5313af801fcf38f594a8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/3f03a2d225c668283110ad5f9ff159ba4591e2c7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/430521af7fe8a9c08f5a2554224a35f11f51d99e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/47b3af24de5fbed4bf2952de0f5294ef1a338a26\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/8dc51351472825500145eed5bddfb88b2ec32008\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c9c9b37f8c5505224e8d206184df3bb668ee00cf\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-09-01T17:22:24+00:00",
      "cve": "CVE-2026-72255",
      "id": "CVE-2026-72255",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "260",
      "product_status:under_investigation": "14",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: netfilter: nf_queue: pin bridge device while NFQUEUE holds fake dst",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72255.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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