{"api_version":"1","generated_at":"2026-07-24T17:42:49+00:00","cve":"CVE-2026-63875","urls":{"html":"https://cve.report/CVE-2026-63875","api":"https://cve.report/api/cve/CVE-2026-63875.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-63875","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-63875"},"summary":{"title":"arm64: tlb: Flush walk cache when unsharing PMD tables","description":"In the Linux kernel, the following vulnerability has been resolved:\n\narm64: tlb: Flush walk cache when unsharing PMD tables\n\nWhen huge_pmd_unshare() is called to unshare a PMD table, the\ntlb_unshare_pmd_ptdesc() function sets tlb->unshared_tables=true\nbut the aarch64 tlb_flush() only checked tlb->freed_tables to\ndetermine whether to use TLBF_NONE (vae1is, invalidates walk\ncache) or TLBF_NOWALKCACHE (vale1is, leaf-only).\n\nThis caused the stale PMD page table entry to remain in the walk cache\nafter unshare, potentially leading to incorrect page table walks.\n\nFix by including unshared_tables in the check, so that when\nunsharing tables, TLBF_NONE is used and the walk cache is properly\ninvalidated.\n\nHere is the detailed distinction between vae1is and vale1is:\n\n| Instruction Combination  | Actual Invalidation Scope                         |\n| ------------------------ | --------------------------------------------------|\n| `VAE1IS`  + TTL=`0`      | All entries at all levels (full invalidation)     |\n| `VAE1IS`  + TTL=`2` (L2) | Non-leaf at Level 0/1 + leaf at Level 2           |\n| `VALE1IS` + TTL=`0`      | Leaf entries at all levels (non-leaf not cleared) |\n| `VALE1IS` + TTL=`2` (L2) | Leaf entry at Level 2 only                        |","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-19 16:17:04","updated_at":"2026-07-20 15:16:53"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"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"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"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"}}],"references":[{"url":"https://git.kernel.org/stable/c/dced308d7d6a0de1c09d2058f38f1aaaf5cbb914","name":"https://git.kernel.org/stable/c/dced308d7d6a0de1c09d2058f38f1aaaf5cbb914","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d766a49d9b55705c4737cd8bb5d3faa2d31330fd","name":"https://git.kernel.org/stable/c/d766a49d9b55705c4737cd8bb5d3faa2d31330fd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/8ca7284da0e67b3e71d90ec17f08286774245ad9","name":"https://git.kernel.org/stable/c/8ca7284da0e67b3e71d90ec17f08286774245ad9","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/fe93e907b1af03cc229a80aa64a570a103d2b279","name":"https://git.kernel.org/stable/c/fe93e907b1af03cc229a80aa64a570a103d2b279","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/47490bbb05c8c0e09cc3cfd237d8934ffc340583","name":"https://git.kernel.org/stable/c/47490bbb05c8c0e09cc3cfd237d8934ffc340583","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c2ff4764e03e7a8d758352f4aceb8fe1be6ac971","name":"https://git.kernel.org/stable/c/c2ff4764e03e7a8d758352f4aceb8fe1be6ac971","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0199c9d57861f17b556b6cba1f765c7cce79745b","name":"https://git.kernel.org/stable/c/0199c9d57861f17b556b6cba1f765c7cce79745b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/48125cd9c55cbe297b59fd1f9bda48b0960bd181","name":"https://git.kernel.org/stable/c/48125cd9c55cbe297b59fd1f9bda48b0960bd181","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-63875","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63875","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6495204f8219a57859669d618b25d06176d5a872 dced308d7d6a0de1c09d2058f38f1aaaf5cbb914 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected ce4cf24761467756462c0e1dbe4a5e9c9eb520fc 47490bbb05c8c0e09cc3cfd237d8934ffc340583 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected daa6707b71a2da23a82979fa21f788aeb706f1a2 0199c9d57861f17b556b6cba1f765c7cce79745b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected ff37dd18ce7739a26aab0cc2d31006a45e6bde63 d766a49d9b55705c4737cd8bb5d3faa2d31330fd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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the Linux kernel, the following vulnerability has been resolved:\n\narm64: tlb: Flush walk cache when unsharing PMD tables\n\nWhen huge_pmd_unshare() is called to unshare a PMD table, the\ntlb_unshare_pmd_ptdesc() function sets tlb->unshared_tables=true\nbut the aarch64 tlb_flush() only checked tlb->freed_tables to\ndetermine whether to use TLBF_NONE (vae1is, invalidates walk\ncache) or TLBF_NOWALKCACHE (vale1is, leaf-only).\n\nThis caused the stale PMD page table entry to remain in the walk cache\nafter unshare, potentially leading to incorrect page table walks.\n\nFix by including unshared_tables in the check, so that when\nunsharing tables, TLBF_NONE is used and the walk cache is properly\ninvalidated.\n\nHere is the detailed distinction between vae1is and vale1is:\n\n| Instruction Combination  | Actual Invalidation Scope                         |\n| ------------------------ | --------------------------------------------------|\n| `VAE1IS`  + TTL=`0`      | All entries at all levels (full invalidation)     |\n| `VAE1IS`  + TTL=`2` (L2) | Non-leaf at Level 0/1 + leaf at Level 2           |\n| `VALE1IS` + TTL=`0`      | Leaf entries at all levels (non-leaf not cleared) |\n| `VALE1IS` + TTL=`2` (L2) | Leaf entry at Level 2 only                        |"}],"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"}}],"providerMetadata":{"dateUpdated":"2026-07-20T13:41:06.339Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/dced308d7d6a0de1c09d2058f38f1aaaf5cbb914"},{"url":"https://git.kernel.org/stable/c/47490bbb05c8c0e09cc3cfd237d8934ffc340583"},{"url":"https://git.kernel.org/stable/c/0199c9d57861f17b556b6cba1f765c7cce79745b"},{"url":"https://git.kernel.org/stable/c/d766a49d9b55705c4737cd8bb5d3faa2d31330fd"},{"url":"https://git.kernel.org/stable/c/8ca7284da0e67b3e71d90ec17f08286774245ad9"},{"url":"https://git.kernel.org/stable/c/fe93e907b1af03cc229a80aa64a570a103d2b279"},{"url":"https://git.kernel.org/stable/c/48125cd9c55cbe297b59fd1f9bda48b0960bd181"},{"url":"https://git.kernel.org/stable/c/c2ff4764e03e7a8d758352f4aceb8fe1be6ac971"}],"title":"arm64: tlb: Flush walk cache when unsharing PMD tables","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-63875","datePublished":"2026-07-19T14:54:48.842Z","dateReserved":"2026-07-19T07:54:57.017Z","dateUpdated":"2026-07-20T13:41:06.339Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-19 16:17:04","lastModifiedDate":"2026-07-20 15:16:53","problem_types":[],"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}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"63875","Ordinal":"1","Title":"arm64: tlb: Flush walk cache when unsharing PMD tables","CVE":"CVE-2026-63875","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"63875","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\narm64: tlb: Flush walk cache when unsharing PMD tables\n\nWhen huge_pmd_unshare() is called to unshare a PMD table, the\ntlb_unshare_pmd_ptdesc() function sets tlb->unshared_tables=true\nbut the aarch64 tlb_flush() only checked tlb->freed_tables to\ndetermine whether to use TLBF_NONE (vae1is, invalidates walk\ncache) or TLBF_NOWALKCACHE (vale1is, leaf-only).\n\nThis caused the stale PMD page table entry to remain in the walk cache\nafter unshare, potentially leading to incorrect page table walks.\n\nFix by including unshared_tables in the check, so that when\nunsharing tables, TLBF_NONE is used and the walk cache is properly\ninvalidated.\n\nHere is the detailed distinction between vae1is and vale1is:\n\n| Instruction Combination  | Actual Invalidation Scope                         |\n| ------------------------ | --------------------------------------------------|\n| `VAE1IS`  + TTL=`0`      | All entries at all levels (full invalidation)     |\n| `VAE1IS`  + TTL=`2` (L2) | Non-leaf at Level 0/1 + leaf at Level 2           |\n| `VALE1IS` + TTL=`0`      | Leaf entries at all levels (non-leaf not cleared) |\n| `VALE1IS` + TTL=`2` (L2) | Leaf entry at Level 2 only                        |","Type":"Description","Title":"arm64: tlb: Flush walk cache when unsharing PMD tables"}]}}}