CVE-2026-64188 (GCVE-0-2026-64188)
Vulnerability from cvelistv5
Published
2026-07-20 16:27
Modified
2026-08-05 12:39
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: net: qualcomm: rmnet: fix endpoint use-after-free in rmnet_dellink() rmnet_dellink() removes the endpoint from the hash table with hlist_del_init_rcu() and then immediately frees it with kfree(). However, RCU readers on the receive path (rmnet_rx_handler -> __rmnet_map_ingress_handler) may still hold a reference to the endpoint and dereference ep->egress_dev after the memory has been freed. The endpoint is a kmalloc-32 object, and the stale read at offset 8 corresponds to the egress_dev pointer. BUG: unable to handle page fault for address: ffffffffde942eef Oops: 0002 [#1] SMP NOPTI CPU: 1 UID: 0 PID: 137 Comm: poc_write Not tainted 7.0.0+ #4 PREEMPTLAZY RIP: 0010:rmnet_vnd_rx_fixup (rmnet_vnd.c:27) Call Trace: <TASK> __rmnet_map_ingress_handler (rmnet_handlers.c:48 rmnet_handlers.c:101) rmnet_rx_handler (rmnet_handlers.c:129 rmnet_handlers.c:235) __netif_receive_skb_core.constprop.0 (net/core/dev.c:6096) __netif_receive_skb_one_core (net/core/dev.c:6208) netif_receive_skb (net/core/dev.c:6467) tun_get_user (drivers/net/tun.c:1955) tun_chr_write_iter (drivers/net/tun.c:2003) vfs_write (fs/read_write.c:688) ksys_write (fs/read_write.c:740) </TASK> Add an rcu_head field to struct rmnet_endpoint and replace kfree() with kfree_rcu() so the endpoint memory remains valid through the RCU grace period. Also remove the rmnet_vnd_dellink() call and inline only the nr_rmnet_devs decrement, since rmnet_vnd_dellink() would set ep->egress_dev to NULL during the grace period, creating a data race with lockless readers.
References
Impacted products
Vendor Product Version
Linux Linux Version: ceed73a2cf4aff2921802aa3d21d45280677547d
Version: ceed73a2cf4aff2921802aa3d21d45280677547d
Version: ceed73a2cf4aff2921802aa3d21d45280677547d
Version: ceed73a2cf4aff2921802aa3d21d45280677547d
Version: ceed73a2cf4aff2921802aa3d21d45280677547d
Version: ceed73a2cf4aff2921802aa3d21d45280677547d
Version: ceed73a2cf4aff2921802aa3d21d45280677547d
Version: ceed73a2cf4aff2921802aa3d21d45280677547d
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{
  "containers": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c",
            "drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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          "programFiles": [
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            "drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
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        }
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      "cpeApplicability": [
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              "negate": false,
              "operator": "OR"
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        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: qualcomm: rmnet: fix endpoint use-after-free in rmnet_dellink()\n\nrmnet_dellink() removes the endpoint from the hash table with\nhlist_del_init_rcu() and then immediately frees it with kfree(). However,\nRCU readers on the receive path (rmnet_rx_handler -\u003e\n__rmnet_map_ingress_handler) may still hold a reference to the endpoint and\ndereference ep-\u003eegress_dev after the memory has been freed. The endpoint is\na kmalloc-32 object, and the stale read at offset 8 corresponds to the\negress_dev pointer.\n\n  BUG: unable to handle page fault for address: ffffffffde942eef\n  Oops: 0002 [#1] SMP NOPTI\n  CPU: 1 UID: 0 PID: 137 Comm: poc_write Not tainted 7.0.0+ #4 PREEMPTLAZY\n  RIP: 0010:rmnet_vnd_rx_fixup (rmnet_vnd.c:27)\n  Call Trace:\n   \u003cTASK\u003e\n   __rmnet_map_ingress_handler (rmnet_handlers.c:48 rmnet_handlers.c:101)\n   rmnet_rx_handler (rmnet_handlers.c:129 rmnet_handlers.c:235)\n   __netif_receive_skb_core.constprop.0 (net/core/dev.c:6096)\n   __netif_receive_skb_one_core (net/core/dev.c:6208)\n   netif_receive_skb (net/core/dev.c:6467)\n   tun_get_user (drivers/net/tun.c:1955)\n   tun_chr_write_iter (drivers/net/tun.c:2003)\n   vfs_write (fs/read_write.c:688)\n   ksys_write (fs/read_write.c:740)\n   \u003c/TASK\u003e\n\nAdd an rcu_head field to struct rmnet_endpoint and replace kfree() with\nkfree_rcu() so the endpoint memory remains valid through the RCU grace\nperiod. Also remove the rmnet_vnd_dellink() call and inline only the\nnr_rmnet_devs decrement, since rmnet_vnd_dellink() would set\nep-\u003eegress_dev to NULL during the grace period, creating a data race\nwith lockless readers."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The complete exploit path is local: attacker-written frames enter through TUN while RTM_DELLINK over NETLINK_ROUTE invokes rmnet_dellink(); remote traffic alone cannot perform the required endpoint deletion.\nAC:L - The attacker controls both sides of the race by concurrently injecting crafted MAP frames and deleting or recreating the RMNET link, allowing repeated attempts without an uncontrollable condition.\nPR:L - Deletion requires CAP_NET_ADMIN in the route socket\u0027s network namespace, which an unprivileged user can obtain through a private user and network namespace to create TUN and RMNET devices.\nUI:N - No separate victim action is required because the attacker directly performs link setup, packet injection, and deletion.\nS:U - Exploitation compromises the kernel within the same security authority and does not cross a VM, IOMMU, or comparable scope boundary.\nC:H - The freed kmalloc-32 endpoint can be reclaimed with attacker-influenced contents, making the stale egress_dev pointer usable for forged-object dereferences and access to sensitive kernel memory.\nI:H - The corrupted egress_dev pointer reaches rmnet_vnd_rx_fixup, where derived per-CPU statistics pointers are written, providing a plausible path to arbitrary memory corruption and control-flow hijacking.\nA:H - The demonstrated race causes a page fault and kernel Oops in rmnet_vnd_rx_fixup, and it can be triggered repeatedly to crash the system."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:39:57.703Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/c4e676c3505c5058922dc1a6f1ded795f6758135"
        },
        {
          "url": "https://git.kernel.org/stable/c/9918698cf3aee4032e12bb42fd5a951dc465339b"
        },
        {
          "url": "https://git.kernel.org/stable/c/310b93246bfec7d4452507e0c15477377ed9f025"
        },
        {
          "url": "https://git.kernel.org/stable/c/1078ae8175777e80c9637996fb4a46c55f0ce576"
        },
        {
          "url": "https://git.kernel.org/stable/c/41e06fcc5df0774d212e70c5b503fc769492bce3"
        },
        {
          "url": "https://git.kernel.org/stable/c/8b17adf6d4fb6bf61fa4c3f58366a7c082799a71"
        },
        {
          "url": "https://git.kernel.org/stable/c/f193e38cb257d033060b63f1cfd94af076b3a2ab"
        },
        {
          "url": "https://git.kernel.org/stable/c/d00c953a8f69921f484b629801766da68f27f658"
        }
      ],
      "title": "net: qualcomm: rmnet: fix endpoint use-after-free in rmnet_dellink()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64188",
    "datePublished": "2026-07-20T16:27:47.216Z",
    "dateReserved": "2026-07-19T07:54:57.040Z",
    "dateUpdated": "2026-08-05T12:39:57.703Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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