{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-64181", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.039Z", "datePublished": "2026-07-19T15:41:04.455Z", "dateUpdated": "2026-07-20T13:44:01.228Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-07-20T13:44:01.228Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: fix __vm_normal_page() to handle missing support for pmd_special()/pud_special()\n\nOn x86 32-bit with THP enabled, zap_huge_pmd() is seen to generate a\n\"WARNING: mm/memory.c:735 at __vm_normal_page+0x6a/0x7d\", from the\nVM_WARN_ON_ONCE(is_zero_pfn(pfn) || is_huge_zero_pfn(pfn)); followed by\n\"BUG: Bad rss-counter state\"s, then later \"BUG: Bad page state\"s when\nreclaim gets to call shrink_huge_zero_folio_scan().\n\nIt's as if the _PAGE_SPECIAL bit never got set in the huge_zero pmd: and\nindeed, whereas pte_special() and pte_mkspecial() are subject to a\ndedicated CONFIG_ARCH_HAS_PTE_SPECIAL, pmd_special() and pmd_mkspecial()\nare subject to CONFIG_ARCH_SUPPORTS_PMD_PFNMAP, which is never enabled on\nany 32-bit architecture.\n\nWhile the problem was exposed through commit d80a9cb1a64a\n(\"mm/huge_memory: add and use normal_or_softleaf_folio_pmd()\"), it was an\noversight in commit af38538801c6 (\"mm/memory: factor out common code from\nvm_normal_page_*()\") and would result in other problems:\n* huge zero folio accounted in smaps, pagemap (PAGE_IS_FILE) and\n numamaps as file-backed THP\n* folio_walk_start() returning the folio even without FW_ZEROPAGE set.\n Callers seem to tolerate that, though.\n\n... and triggering the VM_WARN_ON_ONE(), although never reported so far.\n\nTo fix it, teach vm_normal_page_pmd()/vm_normal_page_pud() to consider\nwhether pmd_special/pud_special is actually implemented."}], "metrics": [{"cvssV3_1": {"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"}}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["mm/memory.c"], "versions": [{"version": "af38538801c6a97565b44700ee6695d7d60ad779", "lessThan": "62153767e8fc3889bc6508e9ffe927aaf64c4334", "status": "affected", "versionType": "git"}, {"version": "af38538801c6a97565b44700ee6695d7d60ad779", "lessThan": "9052ea2ee2233be5d4786b8909151ca2bfbedf99", "status": "affected", "versionType": "git"}, {"version": "af38538801c6a97565b44700ee6695d7d60ad779", "lessThan": "c0c6ccd9828c3a1950623b546fa57292a77b5c73", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["mm/memory.c"], "versions": [{"version": "6.18", "status": "affected"}, {"version": "0", "lessThan": "6.18", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.34", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.0.11", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18", "versionEndExcluding": "6.18.34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18", "versionEndExcluding": "7.0.11"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18", "versionEndExcluding": "7.1"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/62153767e8fc3889bc6508e9ffe927aaf64c4334"}, {"url": "https://git.kernel.org/stable/c/9052ea2ee2233be5d4786b8909151ca2bfbedf99"}, {"url": "https://git.kernel.org/stable/c/c0c6ccd9828c3a1950623b546fa57292a77b5c73"}], "title": "mm: fix __vm_normal_page() to handle missing support for pmd_special()/pud_special()", "x_generator": {"engine": "bippy-1.2.0"}}}}

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{"bugzilla": {"description": "kernel: mm: fix __vm_normal_page() to handle missing support for pmd_special()/pud_special()", "id": "2502516", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2502516"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-166", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nmm: fix __vm_normal_page() to handle missing support for pmd_special()/pud_special()\nOn x86 32-bit with THP enabled, zap_huge_pmd() is seen to generate a\n\"WARNING: mm/memory.c:735 at __vm_normal_page+0x6a/0x7d\", from the\nVM_WARN_ON_ONCE(is_zero_pfn(pfn) || is_huge_zero_pfn(pfn)); followed by\n\"BUG: Bad rss-counter state\"s, then later \"BUG: Bad page state\"s when\nreclaim gets to call shrink_huge_zero_folio_scan().\nIt's as if the _PAGE_SPECIAL bit never got set in the huge_zero pmd: and\nindeed, whereas pte_special() and pte_mkspecial() are subject to a\ndedicated CONFIG_ARCH_HAS_PTE_SPECIAL, pmd_special() and pmd_mkspecial()\nare subject to CONFIG_ARCH_SUPPORTS_PMD_PFNMAP, which is never enabled on\nany 32-bit architecture.\nWhile the problem was exposed through commit d80a9cb1a64a\n(\"mm/huge_memory: add and use normal_or_softleaf_folio_pmd()\"), it was an\noversight in commit af38538801c6 (\"mm/memory: factor out common code from\nvm_normal_page_*()\") and would result in other problems:\n* huge zero folio accounted in smaps, pagemap (PAGE_IS_FILE) and\nnumamaps as file-backed THP\n* folio_walk_start() returning the folio even without FW_ZEROPAGE set.\nCallers seem to tolerate that, though.\n... and triggering the VM_WARN_ON_ONE(), although never reported so far.\nTo fix it, teach vm_normal_page_pmd()/vm_normal_page_pud() to consider\nwhether pmd_special/pud_special is actually implemented.", "A flaw was found in the Linux kernel's memory management subsystem. On 32-bit x86 systems with Transparent Huge Pages (THP) enabled, a missing feature for handling special page table entries can lead to incorrect tracking of memory resources. This can result in system warnings, errors related to memory state, and misrepresentation of memory usage, potentially impacting system stability and resource monitoring."], "name": "CVE-2026-64181", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-07-19T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-64181\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-64181\nhttps://lore.kernel.org/linux-cve-announce/2026071938-CVE-2026-64181-e460@gregkh/T"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[af38538801c6a97565b44700ee6695d7d60ad779,62153767e8fc3889bc6508e9ffe927aaf64c4334)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[af38538801c6a97565b44700ee6695d7d60ad779,9052ea2ee2233be5d4786b8909151ca2bfbedf99)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[af38538801c6a97565b44700ee6695d7d60ad779,c0c6ccd9828c3a1950623b546fa57292a77b5c73)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "6.18"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0,6.18)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.34,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.0.11,7.1.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.1,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-07-21T11:45:03.654298+00:00", "updated": "2026-07-21T11:45:03.654341+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}