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CVE-2026-23458 (GCVE-0-2026-23458)

Vulnerability from cvelistv5 – Published: 2026-04-03 15:15 – Updated: 2026-09-08 08:46
VLAI
Title
netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct() ctnetlink_dump_exp_ct() stores a conntrack pointer in cb->data for the netlink dump callback ctnetlink_exp_ct_dump_table(), but drops the conntrack reference immediately after netlink_dump_start(). When the dump spans multiple rounds, the second recvmsg() triggers the dump callback which dereferences the now-freed conntrack via nfct_help(ct), leading to a use-after-free on ct->ext. The bug is that the netlink_dump_control has no .start or .done callbacks to manage the conntrack reference across dump rounds. Other dump functions in the same file (e.g. ctnetlink_get_conntrack) properly use .start/.done callbacks for this purpose. Fix this by adding .start and .done callbacks that hold and release the conntrack reference for the duration of the dump, and move the nfct_help() call after the cb->args[0] early-return check in the dump callback to avoid dereferencing ct->ext unnecessarily. BUG: KASAN: slab-use-after-free in ctnetlink_exp_ct_dump_table+0x4f/0x2e0 Read of size 8 at addr ffff88810597ebf0 by task ctnetlink_poc/133 CPU: 1 UID: 0 PID: 133 Comm: ctnetlink_poc Not tainted 7.0.0-rc2+ #3 PREEMPTLAZY Call Trace: <TASK> ctnetlink_exp_ct_dump_table+0x4f/0x2e0 netlink_dump+0x333/0x880 netlink_recvmsg+0x3e2/0x4b0 ? aa_sk_perm+0x184/0x450 sock_recvmsg+0xde/0xf0 Allocated by task 133: kmem_cache_alloc_noprof+0x134/0x440 __nf_conntrack_alloc+0xa8/0x2b0 ctnetlink_create_conntrack+0xa1/0x900 ctnetlink_new_conntrack+0x3cf/0x7d0 nfnetlink_rcv_msg+0x48e/0x510 netlink_rcv_skb+0xc9/0x1f0 nfnetlink_rcv+0xdb/0x220 netlink_unicast+0x3ec/0x590 netlink_sendmsg+0x397/0x690 __sys_sendmsg+0xf4/0x180 Freed by task 0: slab_free_after_rcu_debug+0xad/0x1e0 rcu_core+0x5c3/0x9c0
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: e844a928431fa8f1359d1f4f2cef53d9b446bf52 , < d8cd0efbccc5cfb0a80da744a7da76e1333ab925 (git)
Affected: e844a928431fa8f1359d1f4f2cef53d9b446bf52 , < 9821b47f669eb82791fa0b1a6ebaf9aa219bea72 (git)
Affected: e844a928431fa8f1359d1f4f2cef53d9b446bf52 , < bdf2724eefd4455a66863abb025bab8d3aa98c57 (git)
Affected: e844a928431fa8f1359d1f4f2cef53d9b446bf52 , < f04cc86d59906513d2d62183b882966fc0ae0390 (git)
Affected: e844a928431fa8f1359d1f4f2cef53d9b446bf52 , < f025171feef2ac65663d7986f1d5ff0c28d6b2a9 (git)
Affected: e844a928431fa8f1359d1f4f2cef53d9b446bf52 , < 04c8907ce4e3d3e26c5e1a3e47aa5d17082cbb56 (git)
Affected: e844a928431fa8f1359d1f4f2cef53d9b446bf52 , < cd541f15b60e2257441398cf495d978f816d09f8 (git)
Affected: e844a928431fa8f1359d1f4f2cef53d9b446bf52 , < 5cb81eeda909dbb2def209dd10636b51549a3f8a (git)
guessed Create a notification for this product.
Linux Linux Affected: 3.10
Unaffected: 0 , < 3.10 (semver)
Unaffected: 5.10.253 , ≤ 5.10.* (semver)
Unaffected: 5.15.203 , ≤ 5.15.* (semver)
Unaffected: 6.1.167 , ≤ 6.1.* (semver)
Unaffected: 6.6.130 , ≤ 6.6.* (semver)
Unaffected: 6.12.78 , ≤ 6.12.* (semver)
Unaffected: 6.18.20 , ≤ 6.18.* (semver)
Unaffected: 6.19.10 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.5 , < * (custom)
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Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP Affected: V3.1.5 , < * (custom)
guessed Create a notification for this product.
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
guessed Create a notification for this product.
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.5 , < * (custom)
guessed Create a notification for this product.
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()\n\nctnetlink_dump_exp_ct() stores a conntrack pointer in cb-\u003edata for the\nnetlink dump callback ctnetlink_exp_ct_dump_table(), but drops the\nconntrack reference immediately after netlink_dump_start().  When the\ndump spans multiple rounds, the second recvmsg() triggers the dump\ncallback which dereferences the now-freed conntrack via nfct_help(ct),\nleading to a use-after-free on ct-\u003eext.\n\nThe bug is that the netlink_dump_control has no .start or .done\ncallbacks to manage the conntrack reference across dump rounds.  Other\ndump functions in the same file (e.g. ctnetlink_get_conntrack) properly\nuse .start/.done callbacks for this purpose.\n\nFix this by adding .start and .done callbacks that hold and release the\nconntrack reference for the duration of the dump, and move the\nnfct_help() call after the cb-\u003eargs[0] early-return check in the dump\ncallback to avoid dereferencing ct-\u003eext unnecessarily.\n\n BUG: KASAN: slab-use-after-free in ctnetlink_exp_ct_dump_table+0x4f/0x2e0\n Read of size 8 at addr ffff88810597ebf0 by task ctnetlink_poc/133\n\n CPU: 1 UID: 0 PID: 133 Comm: ctnetlink_poc Not tainted 7.0.0-rc2+ #3 PREEMPTLAZY\n Call Trace:\n  \u003cTASK\u003e\n  ctnetlink_exp_ct_dump_table+0x4f/0x2e0\n  netlink_dump+0x333/0x880\n  netlink_recvmsg+0x3e2/0x4b0\n  ? aa_sk_perm+0x184/0x450\n  sock_recvmsg+0xde/0xf0\n\n Allocated by task 133:\n  kmem_cache_alloc_noprof+0x134/0x440\n  __nf_conntrack_alloc+0xa8/0x2b0\n  ctnetlink_create_conntrack+0xa1/0x900\n  ctnetlink_new_conntrack+0x3cf/0x7d0\n  nfnetlink_rcv_msg+0x48e/0x510\n  netlink_rcv_skb+0xc9/0x1f0\n  nfnetlink_rcv+0xdb/0x220\n  netlink_unicast+0x3ec/0x590\n  netlink_sendmsg+0x397/0x690\n  __sys_sendmsg+0xf4/0x180\n\n Freed by task 0:\n  slab_free_after_rcu_debug+0xad/0x1e0\n  rcu_core+0x5c3/0x9c0"
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              "value": "AV:L - The vulnerable path is reached through a local NETLINK_NETFILTER ctnetlink request, specifically an expectation dump with CTA_EXPECT_MASTER. It is not reachable directly from unauthenticated network packets.\nAC:L - The attacker can create the relevant conntrack/expectation state, start the multipart dump, and free the master conntrack before the next recvmsg. No condition outside attacker control or difficult race is required.\nPR:L - nfnetlink requires CAP_NET_ADMIN, but the check is against the socket network namespace and is reachable by an unprivileged user via user and network namespaces. This makes the required privilege low rather than high.\nUI:N - Exploitation is driven entirely by attacker-issued netlink operations. No victim user action is required.\nS:U - The impact is within the kernel and the same local system security authority. This is a standard local kernel memory-corruption issue, not a cross-scope boundary escape such as guest-to-host.\nC:H - The bug is a use-after-free of a conntrack object and its extension pointer during a netlink dump. A freed kernel object can plausibly be reclaimed and shaped for information disclosure, so confidentiality impact is high.\nI:H - Use-after-free in kernel heap memory can plausibly be leveraged beyond a crash into memory corruption or control-flow manipulation. Following the required conservative scoring, integrity impact is high.\nA:H - The reported failure is a KASAN slab-use-after-free in kernel netlink dump handling and can cause an oops or panic. The attacker can trigger it repeatedly through local netlink requests."
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        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()\n\nctnetlink_dump_exp_ct() stores a conntrack pointer in cb-\u003edata for the\nnetlink dump callback ctnetlink_exp_ct_dump_table(), but drops the\nconntrack reference immediately after netlink_dump_start().  When the\ndump spans multiple rounds, the second recvmsg() triggers the dump\ncallback which dereferences the now-freed conntrack via nfct_help(ct),\nleading to a use-after-free on ct-\u003eext.\n\nThe bug is that the netlink_dump_control has no .start or .done\ncallbacks to manage the conntrack reference across dump rounds.  Other\ndump functions in the same file (e.g. ctnetlink_get_conntrack) properly\nuse .start/.done callbacks for this purpose.\n\nFix this by adding .start and .done callbacks that hold and release the\nconntrack reference for the duration of the dump, and move the\nnfct_help() call after the cb-\u003eargs[0] early-return check in the dump\ncallback to avoid dereferencing ct-\u003eext unnecessarily.\n\n BUG: KASAN: slab-use-after-free in ctnetlink_exp_ct_dump_table+0x4f/0x2e0\n Read of size 8 at addr ffff88810597ebf0 by task ctnetlink_poc/133\n\n CPU: 1 UID: 0 PID: 133 Comm: ctnetlink_poc Not tainted 7.0.0-rc2+ #3 PREEMPTLAZY\n Call Trace:\n  \u003cTASK\u003e\n  ctnetlink_exp_ct_dump_table+0x4f/0x2e0\n  netlink_dump+0x333/0x880\n  netlink_recvmsg+0x3e2/0x4b0\n  ? aa_sk_perm+0x184/0x450\n  sock_recvmsg+0xde/0xf0\n\n Allocated by task 133:\n  kmem_cache_alloc_noprof+0x134/0x440\n  __nf_conntrack_alloc+0xa8/0x2b0\n  ctnetlink_create_conntrack+0xa1/0x900\n  ctnetlink_new_conntrack+0x3cf/0x7d0\n  nfnetlink_rcv_msg+0x48e/0x510\n  netlink_rcv_skb+0xc9/0x1f0\n  nfnetlink_rcv+0xdb/0x220\n  netlink_unicast+0x3ec/0x590\n  netlink_sendmsg+0x397/0x690\n  __sys_sendmsg+0xf4/0x180\n\n Freed by task 0:\n  slab_free_after_rcu_debug+0xad/0x1e0\n  rcu_core+0x5c3/0x9c0"
          },
          {
            "lang": "es",
            "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnetfilter: ctnetlink: corrige uso despu\u00e9s de liberaci\u00f3n en ctnetlink_dump_exp_ct()\n\nctnetlink_dump_exp_ct() almacena un puntero conntrack en cb -\u003e data para la devoluci\u00f3n de llamada de volcado netlink ctnetlink_exp_ct_dump_table(), pero libera la referencia conntrack inmediatamente despu\u00e9s de netlink_dump_start(). Cuando el volcado abarca m\u00faltiples rondas, el segundo recvmsg() activa la devoluci\u00f3n de llamada de volcado que desreferencia el conntrack ahora liberado a trav\u00e9s de nfct_help(ct), lo que lleva a un uso despu\u00e9s de liberaci\u00f3n en ct -\u003e ext.\n\nEl error es que netlink_dump_control no tiene devoluciones de llamada .start o .done para gestionar la referencia conntrack a trav\u00e9s de las rondas de volcado. Otras funciones de volcado en el mismo archivo (p. ej., ctnetlink_get_conntrack) utilizan correctamente las devoluciones de llamada .start/.done para este prop\u00f3sito.\n\nSolucione esto a\u00f1adiendo devoluciones de llamada .start y .done que retienen y liberan la referencia conntrack durante la duraci\u00f3n del volcado, y mueva la llamada a nfct_help() despu\u00e9s de la comprobaci\u00f3n de retorno anticipado cb -\u003e args[0] en la devoluci\u00f3n de llamada de volcado para evitar desreferenciar ct -\u003e ext innecesariamente.\n\n ERROR: KASAN: uso despu\u00e9s de liberaci\u00f3n de slab en ctnetlink_exp_ct_dump_table+0x4f/0x2e0\n Lectura de tama\u00f1o 8 en la direcci\u00f3n ffff88810597ebf0 por la tarea ctnetlink_poc/133\n\n CPU: 1 UID: 0 PID: 133 Comm: ctnetlink_poc No contaminado 7.0.0-rc2+ #3 PREEMPTLAZY\n Traza de Llamada:\n  \u003cTAREA\u003e\n  ctnetlink_exp_ct_dump_table+0x4f/0x2e0\n  netlink_dump+0x333/0x880\n  netlink_recvmsg+0x3e2/0x4b0\n  ? aa_sk_perm+0x184/0x450\n  sock_recvmsg+0xde/0xf0\n\n Asignado por la tarea 133:\n  kmem_cache_alloc_noprof+0x134/0x440\n  __nf_conntrack_alloc+0xa8/0x2b0\n  ctnetlink_create_conntrack+0xa1/0x900\n  ctnetlink_new_conntrack+0x3cf/0x7d0\n  nfnetlink_rcv_msg+0x48e/0x510\n  netlink_rcv_skb+0xc9/0x1f0\n  nfnetlink_rcv+0xdb/0x220\n  netlink_unicast+0x3ec/0x590\n  netlink_sendmsg+0x397/0x690\n  __sys_sendmsg+0xf4/0x180\n\n Liberado por la tarea 0:\n  slab_free_after_rcu_debug+0xad/0x1e0\n  rcu_core+0x5c3/0x9c0"
          }
        ],
        "id": "CVE-2026-23458",
        "lastModified": "2026-07-24T22:10:00.140",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 1.8,
              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
            }
          ]
        },
        "published": "2026-04-03T16:16:32.647",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
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            "url": "https://git.kernel.org/stable/c/04c8907ce4e3d3e26c5e1a3e47aa5d17082cbb56"
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            "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
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            "url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Modified",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-416"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-06-30T11:52:53+00:00",
      "cve": "CVE-2026-23458",
      "id": "CVE-2026-23458",
      "initial_release_date": "2026-04-03T00:00:00+00:00",
      "product_status:known_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23458.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-09-11T01:35:51Z",
      "cve": "CVE-2026-23458",
      "id": "CVE-2026-23458",
      "initial_release_date": "2026-04-03T23:27:21Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "513",
      "product_status:known_not_affected": "4",
      "product_status:recommended": "509",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-23458",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-23458.json",
      "version": "28"
    }
  }
}



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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

Author Source Type Date Other

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.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.