CVE-2026-64004 (GCVE-0-2026-64004)
Vulnerability from cvelistv5
Published
2026-07-19 14:56
Modified
2026-08-05 12:38
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/iucv: fix locking in .getsockopt Mirror iucv_sock_setsockopt() and wrap the whole switch in lock_sock()/release_sock(). The pre-existing SO_MSGLIMIT-only lock becomes redundant and is removed. Any AF_IUCV HIPER user can potentially crash the kernel by racing recvmsg() with getsockopt(SO_MSGSIZE): the SO_MSGSIZE arm dereferences iucv->hs_dev->mtu after iucv_sock_close() (called from the racing recvmsg()) has set hs_dev to NULL, producing a NULL pointer dereference oops.
References
Impacted products
Vendor Product Version
Linux Linux Version: 51363b8751a673a00ad48eea895266396d53fa52
Version: 51363b8751a673a00ad48eea895266396d53fa52
Version: 51363b8751a673a00ad48eea895266396d53fa52
Version: 51363b8751a673a00ad48eea895266396d53fa52
Version: 51363b8751a673a00ad48eea895266396d53fa52
Version: 51363b8751a673a00ad48eea895266396d53fa52
Version: 51363b8751a673a00ad48eea895266396d53fa52
Version: 51363b8751a673a00ad48eea895266396d53fa52
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{
  "containers": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/iucv/af_iucv.c"
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              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.259",
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                  "versionEndExcluding": "7.1",
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/iucv: fix locking in .getsockopt\n\nMirror iucv_sock_setsockopt() and wrap the whole switch in\nlock_sock()/release_sock(). The pre-existing SO_MSGLIMIT-only lock\nbecomes redundant and is removed.\n\nAny AF_IUCV HIPER user can potentially crash the kernel by racing\nrecvmsg() with getsockopt(SO_MSGSIZE): the SO_MSGSIZE arm dereferences\niucv-\u003ehs_dev-\u003emtu after iucv_sock_close() (called from the racing\nrecvmsg()) has set hs_dev to NULL, producing a NULL pointer dereference\noops."
        }
      ],
      "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 flaw is reached through the getsockopt(2) syscall on an AF_IUCV HIPER socket; the generic socket layer does not acquire the socket lock before calling iucv_sock_getsockopt(), so exploitation requires local access to the socket file descriptor.\nAC:L - The attacker controls both sides of the race by running concurrent getsockopt(SO_MSGSIZE) and recvmsg()/close() threads on the same socket, making the window reliably winnable without external timing luck.\nPR:L - The fix commit explicitly states any AF_IUCV HIPER user can trigger the crash, and iucv_sock_create imposes no capability or root requirement beyond creating and binding a HiperSockets AF_IUCV socket on s390.\nUI:N - Exploitation requires no action from any other user; the attacker races their own syscalls on a socket they control.\nS:U - The impact is a kernel oops or crash within the same kernel security boundary, with no cross-VM, cross-container, or IOMMU boundary crossing.\nC:H - The unlocked TOCTOU between the hs_dev NULL check and dereference races with dev_put() freeing the net_device, creating a use-after-free read whose mtu field is copied to userspace via copy_to_user.\nI:H - Use-after-free on a freed net_device structure in kernel heap memory is a memory corruption primitive that could be further leveraged for control-flow hijacking, and per kernel CVSS guidance UAF bugs warrant High integrity impact.\nA:H - Successful exploitation produces a NULL pointer dereference oops or kernel panic, causing complete loss of availability on the affected IBM Z LPAR or guest."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:38:04.824Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/884eb247b74d86db97e3a37f0d6fc8e1e83590dd"
        },
        {
          "url": "https://git.kernel.org/stable/c/45bb8de8c95d8899f4b8f61bd9bceb8132af73cb"
        },
        {
          "url": "https://git.kernel.org/stable/c/1fc30bd4e55e2dd622d2d366cecd732c1841bbee"
        },
        {
          "url": "https://git.kernel.org/stable/c/cd691beafea0dd779e69e81ccc26b0ab50efcb5e"
        },
        {
          "url": "https://git.kernel.org/stable/c/6e792b8dd3002bbc4136745928a9605df1a72b8a"
        },
        {
          "url": "https://git.kernel.org/stable/c/9817369243380e287ebe5525411557eaa3aa2a79"
        },
        {
          "url": "https://git.kernel.org/stable/c/69554adc7a6fa04ede3ad7512321d83748e3c920"
        },
        {
          "url": "https://git.kernel.org/stable/c/3589d20a666caf30ad100c960a2de7de390fce88"
        }
      ],
      "title": "net/iucv: fix locking in .getsockopt",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64004",
    "datePublished": "2026-07-19T14:56:20.895Z",
    "dateReserved": "2026-07-19T07:54:57.026Z",
    "dateUpdated": "2026-08-05T12:38:04.824Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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