CVE-2025-40133 (GCVE-0-2025-40133)
Vulnerability from cvelistv5
Published
2025-11-12 10:23
Modified
2026-08-05 12:07
Severity ?
8.1 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: mptcp: Use __sk_dst_get() and dst_dev_rcu() in mptcp_active_enable(). mptcp_active_enable() is called from subflow_finish_connect(), which is icsk->icsk_af_ops->sk_rx_dst_set() and it's not always under RCU. Using sk_dst_get(sk)->dev could trigger UAF. Let's use __sk_dst_get() and dst_dev_rcu().
References
Impacted products
Vendor Product Version
Linux Linux Version: 27069e7cb3d1cea9377069266acf19b9cc5ad0ae
Version: 27069e7cb3d1cea9377069266acf19b9cc5ad0ae
Version: 27069e7cb3d1cea9377069266acf19b9cc5ad0ae
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/ctrl.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "ad16235c9d3ef7ec17c109ff39b7504f49d17072",
              "status": "affected",
              "version": "27069e7cb3d1cea9377069266acf19b9cc5ad0ae",
              "versionType": "git"
            },
            {
              "lessThan": "cc976ec9e38bb79409de3261ba1dbb6868e2a53e",
              "status": "affected",
              "version": "27069e7cb3d1cea9377069266acf19b9cc5ad0ae",
              "versionType": "git"
            },
            {
              "lessThan": "893c49a78d9f85e4b8081b908fb7c407d018106a",
              "status": "affected",
              "version": "27069e7cb3d1cea9377069266acf19b9cc5ad0ae",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/ctrl.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.12"
            },
            {
              "lessThan": "6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.55",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.17.*",
              "status": "unaffected",
              "version": "6.17.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.18",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.55",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17.3",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: Use __sk_dst_get() and dst_dev_rcu() in mptcp_active_enable().\n\nmptcp_active_enable() is called from subflow_finish_connect(),\nwhich is icsk-\u003eicsk_af_ops-\u003esk_rx_dst_set() and it\u0027s not always\nunder RCU.\n\nUsing sk_dst_get(sk)-\u003edev could trigger UAF.\n\nLet\u0027s use __sk_dst_get() and dst_dev_rcu()."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The stale `dst-\u003edev` dereference executes while processing a remote peer\u0027s SYN-ACK \u2014 `tcp_finish_connect()` \u2192 `icsk_af_ops-\u003esk_rx_dst_set()` \u2192 `subflow_finish_connect()` \u2192 `mptcp_active_enable()` \u2014 so remote network data drives entry into the vulnerable code, and the peer also controls the MP_CAPABLE/blackhole state that unlocks the guarded block. Any MPTCP-enabled host making outbound connections (mobile/carrier stacks, mptcpize\u0027d services, MPTCP proxies) is exposed to a malicious or on-path server.\nAC:H - The attacker controls one side of the race (when the SYN-ACK arrives and thus when `dst-\u003edev` is read), but the other side requires the route\u0027s `net_device` to be concurrently unregistered so `dst_dev_put()`/`netdev_ref_replace()` drops the last reference and `free_netdev()` runs \u2014 a local netdev-teardown event a remote peer can neither induce nor time, as is landing the SYN-ACK in the socket backlog (non-RCU process context) rather than softirq.\nPR:N - The vulnerable code runs during the TCP/MPTCP handshake itself, before any application-level authentication or credential exchange, so the remote peer needs no privileges or account of any kind on the target.\nUI:N - Outbound MPTCP connections are made automatically by daemons, mobile connectivity stacks, and proxies without any human action, and an on-path attacker can simply inject the MP_CAPABLE SYN-ACK for a connection the host initiates on its own.\nS:U - The use-after-free is on a kernel `struct net_device` and its effects stay within the kernel\u0027s own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - This is a use-after-free read of a freed, heap-sprayable `net_device`, and a reclaimed slab can be groomed with attacker-influenced data, giving a read primitive over reclaimed kernel memory; the value read (`dev-\u003eflags \u0026 IFF_LOOPBACK`) further acts as an oracle since it determines whether `active_disable_times` is cleared, which is observable through subsequent MPTCP fallback behaviour and the MPTCP MIB counters.\nI:H - A use-after-free on a `net_device` is a heap-corruption primitive whose reclaimed contents are attacker-influenceable via spraying, and here freed memory directly steers a kernel state write (`atomic_set(\u0026pernet-\u003eactive_disable_times, 0)`), letting uncontrolled reclaimed data modify per-namespace MPTCP protocol state and, once the slab is groomed, be escalated toward arbitrary write and control-flow hijack.\nA:H - Dereferencing a freed `net_device` \u2014 allocated with `kvzalloc` and potentially unmapped on free \u2014 reliably produces a kernel oops or panic even when not weaponized, and the trigger can be retried indefinitely for a persistent denial of service."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:07:59.353Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/ad16235c9d3ef7ec17c109ff39b7504f49d17072"
        },
        {
          "url": "https://git.kernel.org/stable/c/cc976ec9e38bb79409de3261ba1dbb6868e2a53e"
        },
        {
          "url": "https://git.kernel.org/stable/c/893c49a78d9f85e4b8081b908fb7c407d018106a"
        }
      ],
      "title": "mptcp: Use __sk_dst_get() and dst_dev_rcu() in mptcp_active_enable().",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40133",
    "datePublished": "2025-11-12T10:23:22.498Z",
    "dateReserved": "2025-04-16T07:20:57.170Z",
    "dateUpdated": "2026-08-05T12:07:59.353Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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