CVE-2026-68086

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{"bugzilla": {"description": "kernel: mm/khugepaged: write all dirty file folios when collapsing", "id": "2513141", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2513141"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-367", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nmm/khugepaged: write all dirty file folios when collapsing\n[There is no upstream commit, as this code was removed by upstream\ncommit 044925f9b565 (\"mm: fs: remove filemap_nr_thps*() functions and their users\")]\nAs-is, khugepaged and writable-file opening exclude each other. A file\ncannot be open writeable and have THPs (because the filesystem is not aware\nof them). khugepaged will never collapse file pages for files that are\nopened writeable. On an open(O_RDWR/O_WRONLY), the page cache for that\nparticular file is dropped. This is fine because nothing could've been\ndirtied.\nHowever, there is an edge-case: collapse_file() might not be able to\ncoexist with concurrent writers, but it can coexist with dirty folios\n(from previous writers). Therefore, the following can happen:\nopen(file, O_RDWR)\nwrite(file)\nclose(file)\nmadvise(file_mapping, MADV_COLLAPSE, some non-dirty range)\nopen(file, O_RDWR)\nnr_thps > 0\ntruncate_inode_pages()\n/* THPs are cleared out, but so are the dirty folios */\nWhen this edge-case happens, there is data loss, as the dirty folios are\nfully discarded.\nFix it by fully writing back the page cache (and waiting) when collapsing\nfile THPs. Doing so provides the guarantee that no dirty folio will be\nobserved while there are active THPs. To fully ensure this is safe, the\ninvalidate_lock needs to be held while doing the writeout, so that\ndo_dentry_open()'s page cache truncation excludes this write-and-wait.\nAs a side effect, move the nr_thps counter bumping outside the i_pages\nlock. This is correct since the counter itself is an atomic_t and the\nproducer <-> consumer correctness is provided by a full memory barrier:\nsmp_mb() in collapse_file()/memory barrier implied by full ordering in\nget_write_access() -> atomic_inc_unless_negative().", "A flaw was found in the Linux kernel's memory management (mm/khugepaged) component. A local user could trigger an edge case where unsaved changes to file data (dirty folios) are improperly discarded. This occurs when a file with previous writes is subjected to a specific sequence of memory advice (madvise) operations for transparent huge pages (THPs), leading to data loss."], "name": "CVE-2026-68086", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "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": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-08-10T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-68086\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-68086\nhttps://lore.kernel.org/linux-cve-announce/2026081059-CVE-2026-68086-84fa@gregkh/T"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[99cb0dbd47a15d395bf3faa78dc122bc5efe3fc0,2dfe9f5c91d0963058f8a5e46e1c2a908382cc46)"}}], "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": "5.4"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,5.4)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.1.4,7.2.0)"}}], "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": "2026-08-10T20:00:03.986808+00:00", "updated": "2026-08-13T10:45:04.009829+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}