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cxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_allowed()

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: cxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_allowed() cxl_payload_from_user_allowed() casts and dereferences the input payload without first verifying its size. When a raw mailbox command is sent with an undersized payload (ie: 1 byte for CXL_MBOX_OP_CLEAR_LOG, which expects a 16-byte UUID), uuid_equal() reads past the allocated buffer, triggering a KASAN splat: BUG: KASAN: slab-out-of-bounds in memcmp+0x176/0x1d0 lib/string.c:683 Read of size 8 at addr ffff88810130f5c0 by task syz.1.62/2258 CPU: 2 UID: 0 PID: 2258 Comm: syz.1.62 Not tainted 6.19.0-dirty #3 PREEMPT(voluntary) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xab/0xe0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xce/0x650 mm/kasan/report.c:482 kasan_report+0xce/0x100 mm/kasan/report.c:595 memcmp+0x176/0x1d0 lib/string.c:683 uuid_equal include/linux/uuid.h:73 [inline] cxl_payload_from_user_allowed drivers/cxl/core/mbox.c:345 [inline] cxl_mbox_cmd_ctor drivers/cxl/core/mbox.c:368 [inline] cxl_validate_cmd_from_user drivers/cxl/core/mbox.c:522 [inline] cxl_send_cmd+0x9c0/0xb50 drivers/cxl/core/mbox.c:643 __cxl_memdev_ioctl drivers/cxl/core/memdev.c:698 [inline] cxl_memdev_ioctl+0x14f/0x190 drivers/cxl/core/memdev.c:713 vfs_ioctl fs

Announced Source revision 1
Original source ↗

CVE-2026-23327

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-23327

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "6179045ccc0c6229dc449afc1701dc7fbd40571f",
        "lessThan": "3555e41737c0f8b5b53a511573661477e3942dee",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6179045ccc0c6229dc449afc1701dc7fbd40571f",
        "lessThan": "483b7eb4b1b2a03235afe1b274732dcf8231d4ec",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6179045ccc0c6229dc449afc1701dc7fbd40571f",
        "lessThan": "dc184ac2f0ba77ae19725ee06ad3ab36bb9d1f61",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6179045ccc0c6229dc449afc1701dc7fbd40571f",
        "lessThan": "7c8a7b7f063b7e7ae9bba4cbaa14a5d2fe3a55e1",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6179045ccc0c6229dc449afc1701dc7fbd40571f",
        "lessThan": "60b5d1f68338aff2c5af0113f04aefa7169c50c2",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "drivers/cxl/core/mbox.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.19"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.19",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.114",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.34",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "6.19.7",
        "versionType": "semver",
        "lessThanOrEqual": "6.19.*"
      },
      {
        "status": "unaffected",
        "version": "7.0",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "drivers/cxl/core/mbox.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-23327

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#46118 · Revision 1
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Publisher date
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