CVE-2026-63810 (GCVE-0-2026-63810)

Vulnerability from cvelistv5 – Published: 2026-07-19 12:02 – Updated: 2026-07-19 12:02
VLAI
Title
block: Avoid mounting the bdev pseudo-filesystem in userspace
Summary
In the Linux kernel, the following vulnerability has been resolved: block: Avoid mounting the bdev pseudo-filesystem in userspace The bdev pseudo-filesystem is an internal kernel filesystem with which userspace should not interfere. Unregister it so that userspace cannot even attempt to mount it. This fixes a bug [1] that occurs when attempting to access files, because the system call move_mount() uses pointers declared in the inode_operations structure, which for the bdev pseudo-filesystem are always equal to 0. `inode->i_op = &empty_iops;` [1] BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page PGD 23380067 P4D 23380067 PUD 23381067 PMD 0 Oops: 0010 [#1] PREEMPT SMP KASAN NOPTI CPU: 2 PID: 17125 Comm: syz-executor.0 Not tainted 6.1.155-syzkaller-00350-g84221fde2681 #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 RIP: 0010:0x0 Call Trace: <TASK> lookup_open.isra.0+0x700/0x1180 fs/namei.c:3460 open_last_lookups fs/namei.c:3550 [inline] path_openat+0x953/0x2700 fs/namei.c:3780 do_filp_open+0x1c5/0x410 fs/namei.c:3810 do_sys_openat2+0x171/0x4d0 fs/open.c:1318 do_sys_open fs/open.c:1334 [inline] __do_sys_openat fs/open.c:1350 [inline] __se_sys_openat fs/open.c:1345 [inline] __x64_sys_openat+0x13c/0x1f0 fs/open.c:1345 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x6e/0xd8 Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 197971e6ffc0a6356b2ba2b22beb42bc0f7e412d (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 3804e6de30ae7b053d53341d9d6944356cf23b40 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 717f721eb67d2dacd3ed5f7495aef2f442e84ce4 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < f73aa66dffcb8e61e78f01b56163ec16a15d06d2 (git)
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Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 6.12.95 , ≤ 6.12.* (semver)
Unaffected: 6.18.38 , ≤ 6.18.* (semver)
Unaffected: 7.1.3 , ≤ 7.1.* (semver)
Unaffected: 7.2-rc1 , ≤ * (original_commit_for_fix)
Create a notification for this product.
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
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              "version": "0",
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              "versionType": "semver"
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblock: Avoid mounting the bdev pseudo-filesystem in userspace\n\nThe bdev pseudo-filesystem is an internal kernel filesystem with which\nuserspace should not interfere. Unregister it so that userspace cannot\neven attempt to mount it.\n\nThis fixes a bug [1] that occurs when attempting to access files,\nbecause the system call move_mount() uses pointers declared in the\ninode_operations structure, which for the bdev pseudo-filesystem\nare always equal to 0. `inode-\u003ei_op = \u0026empty_iops;`\n\n[1]\n\n BUG: kernel NULL pointer dereference, address: 0000000000000000\n #PF: supervisor instruction fetch in kernel mode\n #PF: error_code(0x0010) - not-present page\n PGD 23380067 P4D 23380067 PUD 23381067 PMD 0\n Oops: 0010 [#1] PREEMPT SMP KASAN NOPTI\n CPU: 2 PID: 17125 Comm: syz-executor.0 Not tainted 6.1.155-syzkaller-00350-g84221fde2681 #0\n Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014\n RIP: 0010:0x0\n\n Call Trace:\n \u003cTASK\u003e\n lookup_open.isra.0+0x700/0x1180 fs/namei.c:3460\n open_last_lookups fs/namei.c:3550 [inline]\n path_openat+0x953/0x2700 fs/namei.c:3780\n do_filp_open+0x1c5/0x410 fs/namei.c:3810\n do_sys_openat2+0x171/0x4d0 fs/open.c:1318\n do_sys_open fs/open.c:1334 [inline]\n __do_sys_openat fs/open.c:1350 [inline]\n __se_sys_openat fs/open.c:1345 [inline]\n __x64_sys_openat+0x13c/0x1f0 fs/open.c:1345\n do_syscall_x64 arch/x86/entry/common.c:51 [inline]\n do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81\n entry_SYSCALL_64_after_hwframe+0x6e/0xd8\n\nFound by Linux Verification Center (linuxtesting.org) with Syzkaller."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-19T12:02:12.484Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/197971e6ffc0a6356b2ba2b22beb42bc0f7e412d"
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        },
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          "url": "https://git.kernel.org/stable/c/f73aa66dffcb8e61e78f01b56163ec16a15d06d2"
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      "title": "block: Avoid mounting the bdev pseudo-filesystem in userspace",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63810",
    "datePublished": "2026-07-19T12:02:12.484Z",
    "dateReserved": "2026-07-19T07:54:57.013Z",
    "dateUpdated": "2026-07-19T12:02:12.484Z",
    "state": "PUBLISHED"
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  "dataVersion": "5.2",
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      "percentile": "0.06518"
    },
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      "cve": "CVE-2026-63810",
      "id": "msrc_CVE-2026-63810",
      "initial_release_date": "2026-07-20T01:02:14.000Z",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
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      "title": "block: Avoid mounting the bdev pseudo-filesystem in userspace",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-63810.json",
      "version": "2"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-63810\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-07-19T12:16:53.910\",\"lastModified\":\"2026-07-19T12:16:53.910\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nblock: Avoid mounting the bdev pseudo-filesystem in userspace\\n\\nThe bdev pseudo-filesystem is an internal kernel filesystem with which\\nuserspace should not interfere. Unregister it so that userspace cannot\\neven attempt to mount it.\\n\\nThis fixes a bug [1] that occurs when attempting to access files,\\nbecause the system call move_mount() uses pointers declared in the\\ninode_operations structure, which for the bdev pseudo-filesystem\\nare always equal to 0. `inode-\u003ei_op = \u0026empty_iops;`\\n\\n[1]\\n\\n BUG: kernel NULL pointer dereference, address: 0000000000000000\\n #PF: supervisor instruction fetch in kernel mode\\n #PF: error_code(0x0010) - not-present page\\n PGD 23380067 P4D 23380067 PUD 23381067 PMD 0\\n Oops: 0010 [#1] PREEMPT SMP KASAN NOPTI\\n CPU: 2 PID: 17125 Comm: syz-executor.0 Not tainted 6.1.155-syzkaller-00350-g84221fde2681 #0\\n Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014\\n RIP: 0010:0x0\\n\\n Call Trace:\\n \u003cTASK\u003e\\n lookup_open.isra.0+0x700/0x1180 fs/namei.c:3460\\n open_last_lookups fs/namei.c:3550 [inline]\\n path_openat+0x953/0x2700 fs/namei.c:3780\\n do_filp_open+0x1c5/0x410 fs/namei.c:3810\\n do_sys_openat2+0x171/0x4d0 fs/open.c:1318\\n do_sys_open fs/open.c:1334 [inline]\\n __do_sys_openat fs/open.c:1350 [inline]\\n __se_sys_openat fs/open.c:1345 [inline]\\n __x64_sys_openat+0x13c/0x1f0 fs/open.c:1345\\n do_syscall_x64 arch/x86/entry/common.c:51 [inline]\\n do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81\\n entry_SYSCALL_64_after_hwframe+0x6e/0xd8\\n\\nFound by Linux Verification Center (linuxtesting.org) with Syzkaller.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"block/bdev.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\"lessThan\":\"197971e6ffc0a6356b2ba2b22beb42bc0f7e412d\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\"lessThan\":\"3804e6de30ae7b053d53341d9d6944356cf23b40\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\"lessThan\":\"717f721eb67d2dacd3ed5f7495aef2f442e84ce4\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\"lessThan\":\"f73aa66dffcb8e61e78f01b56163ec16a15d06d2\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"block/bdev.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"2.6.12\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"2.6.12\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.95\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.38\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.3\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/197971e6ffc0a6356b2ba2b22beb42bc0f7e412d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/3804e6de30ae7b053d53341d9d6944356cf23b40\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/717f721eb67d2dacd3ed5f7495aef2f442e84ce4\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f73aa66dffcb8e61e78f01b56163ec16a15d06d2\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-07-21T09:08:07+00:00",
      "cve": "CVE-2026-63810",
      "id": "CVE-2026-63810",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: block: Avoid mounting the bdev pseudo-filesystem in userspace",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63810.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.