{"id":"CVE-2026-89961","title":"In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/mm: fix wrong addr_pfn tracking in compound vmemmap population\n\nvmemmap_populate_compound_pages() uses addr_pfn to determine the PFN\noffset within a compound pa…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/mm: fix wrong addr_pfn tracking in compound vmemmap population\n\nvmemmap_populate_compound_pages() uses addr_pfn to determine the PFN\noffset within a compound pa…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","vendor":"Linux","product":"Linux","affected":["Linux >= f2b79c0d79683d552369bb9a7282c1f0226fc566 < b96be860673f9fbbf12cdadb0b25fc4d6d4d207f","Linux >= f2b79c0d79683d552369bb9a7282c1f0226fc566 < e163c7184acf36ac20a248498f4a16016057ca01","Linux >= f2b79c0d79683d552369bb9a7282c1f0226fc566 < 9c914b7a0bd18834505c65f22225ce22c152b2d9","Linux >= f2b79c0d79683d552369bb9a7282c1f0226fc566 < 7968852a7ca3ce81477ec5b4494a28d612f35a97","Linux >= f2b79c0d79683d552369bb9a7282c1f0226fc566 < 89a4ae32764172468dea303eb6ae90fe6c859712","Linux 6.6"],"published":"2026-09-16","updated":"2026-09-16","sourceUpdated":"2026-09-16T15:18:20.703","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-89961","references":[{"url":"https://git.kernel.org/stable/c/7968852a7ca3ce81477ec5b4494a28d612f35a97","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/89a4ae32764172468dea303eb6ae90fe6c859712","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9c914b7a0bd18834505c65f22225ce22c152b2d9","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/b96be860673f9fbbf12cdadb0b25fc4d6d4d207f","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e163c7184acf36ac20a248498f4a16016057ca01","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89961.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89961"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2535116"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89961"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89961"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89961.mbox"},{"url":"https://kernelcve.org/list/?q=CVE-2026-89961"}],"tags":["nvd","cve.org","csaf","vex","red-hat","score-dispute"],"ingestedAt":"2026-09-16T10:53:53.959Z","epss":0.00175,"epssPercentile":0.06965,"cwe":["CWE-682"],"scores":{"nvd":7.8,"vendor":5.5},"slug":"CVE-2026-89961","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/mm: fix wrong addr_pfn tracking in compound vmemmap population\n\nvmemmap_populate_compound_pages() uses addr_pfn to determine the PFN\noffset within a compound page and to decide whether the current vmemmap\nslot should be populated as a head page mapping or should reuse a tail\npage mapping.\n\nHowever, addr_pfn is advanced manually in parallel with addr.  The loop\nitself progresses in vmemmap address space, so each PAGE_SIZE step in addr\ncovers PAGE_SIZE / sizeof(struct page) struct page slots.  Since addr_pfn\nis compared against nr_pages in data-PFN units, it should advance by the\nsame number of PFNs.  The existing manual increments do not match that and\ntherefore do not reliably track the PFN corresponding to the current addr.\n\nAs a result, pfn_offset can be computed from the wrong PFN and the code\ncan make the head/tail decision for the wrong compound-page position.\n\nFix this by deriving addr_pfn directly from the current vmemmap address\ninstead of carrying it as loop state.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89961.json)","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":205085,"id":"CVE-2026-89961","ts":1789570705165,"field":"cvss","old":null,"new":"7.8"},{"seq":205084,"id":"CVE-2026-89961","ts":1789570705165,"field":"severity","old":"none","new":"high"}]}