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CVE-2026-72435 (GCVE-0-2026-72435)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:44
VLAI
Title
netfilter: ipset: fix order of kfree_rcu() and rcu_assign_pointer()
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: ipset: fix order of kfree_rcu() and rcu_assign_pointer() Sashiko pointed out that kfree_rcu() was called before rcu_assign_pointer() in handling the comment extension. Fix the order so that rcu_assign_pointer() called first.
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: b57b2d1fa53fe8563bdfc66a33b844463b9af285 , < c9787d7c24ffd83019f379455e1b97fb4f0f75eb (git)
Affected: b57b2d1fa53fe8563bdfc66a33b844463b9af285 , < 6e98407cb94e035bba98956adc9096a76d8b2a9f (git)
Affected: b57b2d1fa53fe8563bdfc66a33b844463b9af285 , < 50b70f56f3baaff46599f59b2d93fa2540120776 (git)
Affected: b57b2d1fa53fe8563bdfc66a33b844463b9af285 , < d01b4b471f0fc5c396af62845e972ccf99cee29a (git)
Affected: b57b2d1fa53fe8563bdfc66a33b844463b9af285 , < fcb565966534909377a16be5f7b065db2e25c8b5 (git)
Affected: b57b2d1fa53fe8563bdfc66a33b844463b9af285 , < 8087bb360a936a6314d22b567e4b861656943eb6 (git)
Affected: b57b2d1fa53fe8563bdfc66a33b844463b9af285 , < 93a775fd67f3ef34949a9523bfa69403ee74efdd (git)
Affected: b57b2d1fa53fe8563bdfc66a33b844463b9af285 , < 3ca9982a8882470aa0ac4e8bb9a552b181d1efcd (git)
guessed Create a notification for this product.
Linux Linux Affected: 4.2
Unaffected: 0 , < 4.2 (semver)
Unaffected: 5.10.261 , ≤ 5.10.* (semver)
Unaffected: 5.15.212 , ≤ 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)
guessed Create a notification for this product.
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ipset: fix order of kfree_rcu() and rcu_assign_pointer()\n\nSashiko pointed out that kfree_rcu() was called before\nrcu_assign_pointer() in handling the comment extension.\nFix the order so that rcu_assign_pointer() called first."
        }
      ],
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            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
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              "lang": "en",
              "value": "AV:L - The bug is reached only through nfnetlink IPSET commands (ADD/DEL/LIST/SAVE) on NETLINK_GENERIC; nfnetlink_rcv() requires CAP_NET_ADMIN and no remote packet path feeds comment free/replace, so kernel CNA guidance treats netfilter/ipset netlink as Local.\nAC:L - LIST/SAVE dump runs asynchronously without holding the nfnl mutex while mtype_list holds rcu_read_lock and calls ip_set_put_comment; an attacker with CAP_NET_ADMIN can concurrently issue ADD/--exist comment replacement, DEL/flush, or timeout GC to hit the kfree_rcu-before-NULL ordering reliably.\nPR:L - nfnetlink_rcv() gates every ipset command on netlink_net_capable(skb, CAP_NET_ADMIN), which resolves to ns_capable(sock_net()-\u003euser_ns, CAP_NET_ADMIN); unprivileged users obtain this inside a user/network namespace via unshare -Urn and fully control per-netns ipset configuration.\nUI:N - Exploitation is fully attacker-driven through netlink: create a comment-enabled set, start LIST/SAVE dump, and concurrently add/delete/flush elements or let timeout GC run; no victim click, mount, or other deliberate action is required beyond ordinary local control.\nS:U - The RCU use-after-free corrupts kernel heap memory and can yield host privilege escalation or crash, but impact stays within the same kernel security authority and does not cross VM/host, container/host, or IOMMU boundaries.\nC:H - Calling kfree_rcu() before rcu_assign_pointer(NULL) lets dump readers under rcu_read_lock still rcu_dereference(comment-\u003ec) and nla_put_string() reads freed ip_set_comment_rcu kmalloc memory\u2014a classic UAF read usable for arbitrary kernel disclosure with heap grooming.\nI:H - Concurrent free and replacement of RCU-managed comment objects lets an attacker reclaim and control freed slab memory, providing standard paths to arbitrary kernel writes, metadata corruption, and control-flow hijack rather than a bounded or crash-only integrity effect.\nA:H - Stale comment pointer dereference during dump or subsequent slab reuse can immediately kernel-oops or panic the host, and the underlying UAF heap corruption can crash or hang the system even when full exploitation is not attempted."
            }
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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      "title": "netfilter: ipset: fix order of kfree_rcu() and rcu_assign_pointer()",
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    "dateReserved": "2026-08-09T03:40:39.929Z",
    "dateUpdated": "2026-08-17T05:44:10.925Z",
    "state": "PUBLISHED"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-19T17:41:34+00:00",
      "cve": "CVE-2026-72435",
      "id": "CVE-2026-72435",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: netfilter: ipset: fix order of kfree_rcu() and rcu_assign_pointer()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72435.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.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.