CVE-2025-40040 (GCVE-0-2025-40040)

Vulnerability from cvelistv5 – Published: 2025-10-28 11:48 – Updated: 2026-08-05 12:07
VLAI
Title
mm/ksm: fix flag-dropping behavior in ksm_madvise
Summary
In the Linux kernel, the following vulnerability has been resolved: mm/ksm: fix flag-dropping behavior in ksm_madvise syzkaller discovered the following crash: (kernel BUG) [ 44.607039] ------------[ cut here ]------------ [ 44.607422] kernel BUG at mm/userfaultfd.c:2067! [ 44.608148] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 44.608814] CPU: 1 UID: 0 PID: 2475 Comm: reproducer Not tainted 6.16.0-rc6 #1 PREEMPT(none) [ 44.609635] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 44.610695] RIP: 0010:userfaultfd_release_all+0x3a8/0x460 <snip other registers, drop unreliable trace> [ 44.617726] Call Trace: [ 44.617926] <TASK> [ 44.619284] userfaultfd_release+0xef/0x1b0 [ 44.620976] __fput+0x3f9/0xb60 [ 44.621240] fput_close_sync+0x110/0x210 [ 44.622222] __x64_sys_close+0x8f/0x120 [ 44.622530] do_syscall_64+0x5b/0x2f0 [ 44.622840] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 44.623244] RIP: 0033:0x7f365bb3f227 Kernel panics because it detects UFFD inconsistency during userfaultfd_release_all(). Specifically, a VMA which has a valid pointer to vma->vm_userfaultfd_ctx, but no UFFD flags in vma->vm_flags. The inconsistency is caused in ksm_madvise(): when user calls madvise() with MADV_UNMEARGEABLE on a VMA that is registered for UFFD in MINOR mode, it accidentally clears all flags stored in the upper 32 bits of vma->vm_flags. Assuming x86_64 kernel build, unsigned long is 64-bit and unsigned int and int are 32-bit wide. This setup causes the following mishap during the &= ~VM_MERGEABLE assignment. VM_MERGEABLE is a 32-bit constant of type unsigned int, 0x8000'0000. After ~ is applied, it becomes 0x7fff'ffff unsigned int, which is then promoted to unsigned long before the & operation. This promotion fills upper 32 bits with leading 0s, as we're doing unsigned conversion (and even for a signed conversion, this wouldn't help as the leading bit is 0). & operation thus ends up AND-ing vm_flags with 0x0000'0000'7fff'ffff instead of intended 0xffff'ffff'7fff'ffff and hence accidentally clears the upper 32-bits of its value. Fix it by changing `VM_MERGEABLE` constant to unsigned long, using the BIT() macro. Note: other VM_* flags are not affected: This only happens to the VM_MERGEABLE flag, as the other VM_* flags are all constants of type int and after ~ operation, they end up with leading 1 and are thus converted to unsigned long with leading 1s. Note 2: After commit 31defc3b01d9 ("userfaultfd: remove (VM_)BUG_ON()s"), this is no longer a kernel BUG, but a WARNING at the same place: [ 45.595973] WARNING: CPU: 1 PID: 2474 at mm/userfaultfd.c:2067 but the root-cause (flag-drop) remains the same. [akpm@linux-foundation.org: rust bindgen wasn't able to handle BIT(), from Miguel]
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 63c17fb8e5a46a16e10e82005748837fd11a2024 , < 850f1ea245bdc0ce6a3fd36bfb80d8cf9647cb71 (git)
Affected: 63c17fb8e5a46a16e10e82005748837fd11a2024 , < 788e5385d0ff69cdba1cabccb9dab8d9647b9239 (git)
Affected: 63c17fb8e5a46a16e10e82005748837fd11a2024 , < b69f19244c2b6475c8a6eb72f0fb0d53509e48cd (git)
Affected: 63c17fb8e5a46a16e10e82005748837fd11a2024 , < 41cb9fd904fe0c39d52e82dd84dc3c96b7aa9693 (git)
Affected: 63c17fb8e5a46a16e10e82005748837fd11a2024 , < 92b82e232b8d8b116ac6e57aeae7a6033db92c60 (git)
Affected: 63c17fb8e5a46a16e10e82005748837fd11a2024 , < ac50c6e0a8f91a02b681af81abb2362fbb67cc18 (git)
Affected: 63c17fb8e5a46a16e10e82005748837fd11a2024 , < 76385629f45740b7888f8fcd83bde955b10f61fe (git)
Affected: 63c17fb8e5a46a16e10e82005748837fd11a2024 , < f04aad36a07cc17b7a5d5b9a2d386ce6fae63e93 (git)
Create a notification for this product.
Linux Linux Affected: 4.6
Unaffected: 0 , < 4.6 (semver)
Unaffected: 5.4.302 , ≤ 5.4.* (semver)
Unaffected: 5.10.247 , ≤ 5.10.* (semver)
Unaffected: 5.15.197 , ≤ 5.15.* (semver)
Unaffected: 6.1.158 , ≤ 6.1.* (semver)
Unaffected: 6.6.114 , ≤ 6.6.* (semver)
Unaffected: 6.12.55 , ≤ 6.12.* (semver)
Unaffected: 6.17.3 , ≤ 6.17.* (semver)
Unaffected: 6.18 , ≤ * (original_commit_for_fix)
Create a notification for this product.
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{
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              "operator": "OR"
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          ]
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/ksm: fix flag-dropping behavior in ksm_madvise\n\nsyzkaller discovered the following crash: (kernel BUG)\n\n[   44.607039] ------------[ cut here ]------------\n[   44.607422] kernel BUG at mm/userfaultfd.c:2067!\n[   44.608148] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI\n[   44.608814] CPU: 1 UID: 0 PID: 2475 Comm: reproducer Not tainted 6.16.0-rc6 #1 PREEMPT(none)\n[   44.609635] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\n[   44.610695] RIP: 0010:userfaultfd_release_all+0x3a8/0x460\n\n\u003csnip other registers, drop unreliable trace\u003e\n\n[   44.617726] Call Trace:\n[   44.617926]  \u003cTASK\u003e\n[   44.619284]  userfaultfd_release+0xef/0x1b0\n[   44.620976]  __fput+0x3f9/0xb60\n[   44.621240]  fput_close_sync+0x110/0x210\n[   44.622222]  __x64_sys_close+0x8f/0x120\n[   44.622530]  do_syscall_64+0x5b/0x2f0\n[   44.622840]  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n[   44.623244] RIP: 0033:0x7f365bb3f227\n\nKernel panics because it detects UFFD inconsistency during\nuserfaultfd_release_all().  Specifically, a VMA which has a valid pointer\nto vma-\u003evm_userfaultfd_ctx, but no UFFD flags in vma-\u003evm_flags.\n\nThe inconsistency is caused in ksm_madvise(): when user calls madvise()\nwith MADV_UNMEARGEABLE on a VMA that is registered for UFFD in MINOR mode,\nit accidentally clears all flags stored in the upper 32 bits of\nvma-\u003evm_flags.\n\nAssuming x86_64 kernel build, unsigned long is 64-bit and unsigned int and\nint are 32-bit wide.  This setup causes the following mishap during the \u0026=\n~VM_MERGEABLE assignment.\n\nVM_MERGEABLE is a 32-bit constant of type unsigned int, 0x8000\u00270000. \nAfter ~ is applied, it becomes 0x7fff\u0027ffff unsigned int, which is then\npromoted to unsigned long before the \u0026 operation.  This promotion fills\nupper 32 bits with leading 0s, as we\u0027re doing unsigned conversion (and\neven for a signed conversion, this wouldn\u0027t help as the leading bit is 0).\n\u0026 operation thus ends up AND-ing vm_flags with 0x0000\u00270000\u00277fff\u0027ffff\ninstead of intended 0xffff\u0027ffff\u00277fff\u0027ffff and hence accidentally clears\nthe upper 32-bits of its value.\n\nFix it by changing `VM_MERGEABLE` constant to unsigned long, using the\nBIT() macro.\n\nNote: other VM_* flags are not affected: This only happens to the\nVM_MERGEABLE flag, as the other VM_* flags are all constants of type int\nand after ~ operation, they end up with leading 1 and are thus converted\nto unsigned long with leading 1s.\n\nNote 2:\nAfter commit 31defc3b01d9 (\"userfaultfd: remove (VM_)BUG_ON()s\"), this is\nno longer a kernel BUG, but a WARNING at the same place:\n\n[   45.595973] WARNING: CPU: 1 PID: 2474 at mm/userfaultfd.c:2067\n\nbut the root-cause (flag-drop) remains the same.\n\n[akpm@linux-foundation.org: rust bindgen wasn\u0027t able to handle BIT(), from Miguel]"
        }
      ],
      "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 bug is reached purely through the madvise(2) syscall (MADV_MERGEABLE/MADV_UNMERGEABLE) on the caller\u0027s own address space, with no network or remote component. Local access to the system is required.\nAC:L - The flag drop is a deterministic C integer-promotion defect that triggers on every MADV_UNMERGEABLE call \u2014 no race, no memory-layout grooming, and no conditions outside the attacker\u0027s control. A short single-threaded reproducer (memfd + MAP_PRIVATE + MADV_MERGEABLE + UFFDIO_REGISTER(MINOR) + MADV_UNMERGEABLE + close) works 100% of the time.\nPR:L - Any unprivileged local user can do this: memfd_create() and MAP_PRIVATE need no capability, and userfaultfd(UFFD_USER_MODE_ONLY) is explicitly allowed to unprivileged callers regardless of vm.unprivileged_userfaultfd or CAP_SYS_PTRACE. The mseal/pkey/shadow-stack flag-drop variants need no special facility at all.\nUI:N - The attacking process performs the entire sequence itself via its own syscalls; no other user or administrator has to open a file, mount anything, or take any action.\nS:U - The corrupted state is the attacker\u0027s own VMA flags and the resulting crash or protection loss stays within the kernel and the process\u0027s own address space, without crossing into a hypervisor, IOMMU, or other security authority.\nC:H - Clearing VM_PKEY_BIT0..4 makes vma_pkey() return 0 and drops _PAGE_PKEY_* from the recomputed page protection, silently revoking MPK-based isolation so an untrusted in-process component can read memory it was walled off from; combined with the VM_SEALED drop (allowing mremap of regions the policy pinned) this yields disclosure of memory the kernel was supposed to keep protected.\nI:H - The wipe silently revokes kernel-enforced write protections: VM_SEALED loss is a full mseal(2) bypass (sealed code/GOT regions become mprotect-able and munmap-able), and VM_SHADOW_STACK loss lets userspace write its own CET shadow stack, defeating control-flow integrity and enabling ROP \u2014 memory the kernel guaranteed immutable becomes attacker-writable.\nA:H - Dropping VM_UFFD_MINOR while leaving vma-\u003evm_userfaultfd_ctx set creates the inconsistency that userfaultfd_release_all() asserts on, producing a kernel BUG()/invalid-opcode panic on close() (a WARNING at mm/userfaultfd.c:2067 after 31defc3b01d9, still fatal under panic_on_warn). Any local user can trigger this at will."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:07:14.111Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/850f1ea245bdc0ce6a3fd36bfb80d8cf9647cb71"
        },
        {
          "url": "https://git.kernel.org/stable/c/788e5385d0ff69cdba1cabccb9dab8d9647b9239"
        },
        {
          "url": "https://git.kernel.org/stable/c/b69f19244c2b6475c8a6eb72f0fb0d53509e48cd"
        },
        {
          "url": "https://git.kernel.org/stable/c/41cb9fd904fe0c39d52e82dd84dc3c96b7aa9693"
        },
        {
          "url": "https://git.kernel.org/stable/c/92b82e232b8d8b116ac6e57aeae7a6033db92c60"
        },
        {
          "url": "https://git.kernel.org/stable/c/ac50c6e0a8f91a02b681af81abb2362fbb67cc18"
        },
        {
          "url": "https://git.kernel.org/stable/c/76385629f45740b7888f8fcd83bde955b10f61fe"
        },
        {
          "url": "https://git.kernel.org/stable/c/f04aad36a07cc17b7a5d5b9a2d386ce6fae63e93"
        }
      ],
      "title": "mm/ksm: fix flag-dropping behavior in ksm_madvise",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40040",
    "datePublished": "2025-10-28T11:48:20.395Z",
    "dateReserved": "2025-04-16T07:20:57.154Z",
    "dateUpdated": "2026-08-05T12:07:14.111Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2025-40040",
      "date": "2026-08-15",
      "epss": "0.00351",
      "percentile": "0.28186"
    },
    "microsoft_vex": {
      "current_release_date": "2026-03-03T14:57:39.000Z",
      "cve": "CVE-2025-40040",
      "id": "msrc_CVE-2025-40040",
      "initial_release_date": "2025-10-02T00:00:00.000Z",
      "product_status:fixed": "2",
      "product_status:known_affected": "3",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "mm/ksm: fix flag-dropping behavior in ksm_madvise",
      "url": "https://msrc.microsoft.com/csaf/vex/2025/msrc_cve-2025-40040.json",
      "version": "5"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-40040\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-10-28T12:15:37.967\",\"lastModified\":\"2026-07-30T06:24:07.317\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nmm/ksm: fix flag-dropping behavior in ksm_madvise\\n\\nsyzkaller discovered the following crash: (kernel BUG)\\n\\n[   44.607039] ------------[ cut here ]------------\\n[   44.607422] kernel BUG at mm/userfaultfd.c:2067!\\n[   44.608148] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI\\n[   44.608814] CPU: 1 UID: 0 PID: 2475 Comm: reproducer Not tainted 6.16.0-rc6 #1 PREEMPT(none)\\n[   44.609635] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\\n[   44.610695] RIP: 0010:userfaultfd_release_all+0x3a8/0x460\\n\\n\u003csnip other registers, drop unreliable trace\u003e\\n\\n[   44.617726] Call Trace:\\n[   44.617926]  \u003cTASK\u003e\\n[   44.619284]  userfaultfd_release+0xef/0x1b0\\n[   44.620976]  __fput+0x3f9/0xb60\\n[   44.621240]  fput_close_sync+0x110/0x210\\n[   44.622222]  __x64_sys_close+0x8f/0x120\\n[   44.622530]  do_syscall_64+0x5b/0x2f0\\n[   44.622840]  entry_SYSCALL_64_after_hwframe+0x76/0x7e\\n[   44.623244] RIP: 0033:0x7f365bb3f227\\n\\nKernel panics because it detects UFFD inconsistency during\\nuserfaultfd_release_all().  Specifically, a VMA which has a valid pointer\\nto vma-\u003evm_userfaultfd_ctx, but no UFFD flags in vma-\u003evm_flags.\\n\\nThe inconsistency is caused in ksm_madvise(): when user calls madvise()\\nwith MADV_UNMEARGEABLE on a VMA that is registered for UFFD in MINOR mode,\\nit accidentally clears all flags stored in the upper 32 bits of\\nvma-\u003evm_flags.\\n\\nAssuming x86_64 kernel build, unsigned long is 64-bit and unsigned int and\\nint are 32-bit wide.  This setup causes the following mishap during the \u0026=\\n~VM_MERGEABLE assignment.\\n\\nVM_MERGEABLE is a 32-bit constant of type unsigned int, 0x8000\u00270000. \\nAfter ~ is applied, it becomes 0x7fff\u0027ffff unsigned int, which is then\\npromoted to unsigned long before the \u0026 operation.  This promotion fills\\nupper 32 bits with leading 0s, as we\u0027re doing unsigned conversion (and\\neven for a signed conversion, this wouldn\u0027t help as the leading bit is 0).\\n\u0026 operation thus ends up AND-ing vm_flags with 0x0000\u00270000\u00277fff\u0027ffff\\ninstead of intended 0xffff\u0027ffff\u00277fff\u0027ffff and hence accidentally clears\\nthe upper 32-bits of its value.\\n\\nFix it by changing `VM_MERGEABLE` constant to unsigned long, using the\\nBIT() macro.\\n\\nNote: other VM_* flags are not affected: This only happens to the\\nVM_MERGEABLE flag, as the other VM_* flags are all constants of type int\\nand after ~ operation, they end up with leading 1 and are thus converted\\nto unsigned long with leading 1s.\\n\\nNote 2:\\nAfter commit 31defc3b01d9 (\\\"userfaultfd: remove (VM_)BUG_ON()s\\\"), this is\\nno longer a kernel BUG, but a WARNING at the same place:\\n\\n[   45.595973] WARNING: CPU: 1 PID: 2474 at mm/userfaultfd.c:2067\\n\\nbut the root-cause (flag-drop) remains the same.\\n\\n[akpm@linux-foundation.org: rust bindgen wasn\u0027t able to handle BIT(), from Miguel]\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"include/linux/mm.h\",\"rust/bindings/bindings_helper.h\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"63c17fb8e5a46a16e10e82005748837fd11a2024\",\"lessThan\":\"850f1ea245bdc0ce6a3fd36bfb80d8cf9647cb71\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"63c17fb8e5a46a16e10e82005748837fd11a2024\",\"lessThan\":\"788e5385d0ff69cdba1cabccb9dab8d9647b9239\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"63c17fb8e5a46a16e10e82005748837fd11a2024\",\"lessThan\":\"b69f19244c2b6475c8a6eb72f0fb0d53509e48cd\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"63c17fb8e5a46a16e10e82005748837fd11a2024\",\"lessThan\":\"41cb9fd904fe0c39d52e82dd84dc3c96b7aa9693\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"63c17fb8e5a46a16e10e82005748837fd11a2024\",\"lessThan\":\"92b82e232b8d8b116ac6e57aeae7a6033db92c60\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"63c17fb8e5a46a16e10e82005748837fd11a2024\",\"lessThan\":\"ac50c6e0a8f91a02b681af81abb2362fbb67cc18\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"63c17fb8e5a46a16e10e82005748837fd11a2024\",\"lessThan\":\"76385629f45740b7888f8fcd83bde955b10f61fe\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"63c17fb8e5a46a16e10e82005748837fd11a2024\",\"lessThan\":\"f04aad36a07cc17b7a5d5b9a2d386ce6fae63e93\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"include/linux/mm.h\",\"rust/bindings/bindings_helper.h\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"4.6\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"4.6\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.4.302\",\"lessThanOrEqual\":\"5.4.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.247\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.197\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.158\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.114\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.55\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.17.3\",\"lessThanOrEqual\":\"6.17.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9},{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":5.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"NVD-CWE-noinfo\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"4.6\",\"versionEndExcluding\":\"5.4.302\",\"matchCriteriaId\":\"92D7EAC7-85AD-4A59-982E-28696A9CB495\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.5\",\"versionEndExcluding\":\"5.10.247\",\"matchCriteriaId\":\"FE19816A-13B7-4862-B963-A4DF36CA766A\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.11\",\"versionEndExcluding\":\"5.15.197\",\"matchCriteriaId\":\"06E8A34D-C8D8-461A-B8F8-0E420CC5E116\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.16\",\"versionEndExcluding\":\"6.1.158\",\"matchCriteriaId\":\"77B0D8DC-487F-497A-8C89-E7C8F6427586\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.2\",\"versionEndExcluding\":\"6.6.114\",\"matchCriteriaId\":\"4EB737C8-40A2-4187-8371-FFB0D2615B8B\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.7\",\"versionEndExcluding\":\"6.12.55\",\"matchCriteriaId\":\"516AE9B7-F899-4BF2-A81C-BAB0A37671FA\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.17.3\",\"matchCriteriaId\":\"F55A160F-1578-4C10-ABCB-F90B7E146ED8\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/41cb9fd904fe0c39d52e82dd84dc3c96b7aa9693\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/76385629f45740b7888f8fcd83bde955b10f61fe\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/788e5385d0ff69cdba1cabccb9dab8d9647b9239\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/850f1ea245bdc0ce6a3fd36bfb80d8cf9647cb71\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/92b82e232b8d8b116ac6e57aeae7a6033db92c60\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/ac50c6e0a8f91a02b681af81abb2362fbb67cc18\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/b69f19244c2b6475c8a6eb72f0fb0d53509e48cd\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/f04aad36a07cc17b7a5d5b9a2d386ce6fae63e93\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-30T08:52:38+00:00",
      "cve": "CVE-2025-40040",
      "id": "CVE-2025-40040",
      "initial_release_date": "2025-10-28T00:00:00+00:00",
      "product_status:known_affected": "198",
      "product_status:known_not_affected": "76",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: mm/ksm: fix flag-dropping behavior in ksm_madvise",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-40040.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-07-19T17:47:06Z",
      "cve": "CVE-2025-40040",
      "id": "CVE-2025-40040",
      "initial_release_date": "2025-10-29T00:25:28Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "436",
      "product_status:recommended": "807",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-40040",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-40040.json",
      "version": "51"
    }
  }
}



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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

Author Source Type Date Other

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.