{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-63875", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.017Z", "datePublished": "2026-07-19T14:54:48.842Z", "dateUpdated": "2026-08-05T12:36:48.899Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:36:48.899Z" }, "descriptions": [ { "lang": "en", "value": "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 |" } ], "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" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable `tlb_flush()` path is only reached through local memory-management syscalls (mmap/munmap/mprotect/mremap/fork) operating on hugetlb VMAs, not through any network-facing kernel service.\nAC:L - An attacker fully controls the trigger sequence—creating shared hugetlbfs mappings (≥1GB PUD-aligned), forking to establish shared PMD tables, and concurrently unmapping/mprotecting/mremapping to force `huge_pmd_unshare()`—with no conditions outside their control.\nPR:L - Exploitation requires only an unprivileged local user capable of mapping shared hugetlb pages via hugetlbfs or SHM_HUGETLB, which is commonly available on arm64 database and container hosts with pre-reserved huge pages.\nUI:N - No victim interaction is required; the attacker sets up and triggers the stale walk-cache condition entirely within processes they control.\nS:U - Impact is confined to kernel memory-management within the same security authority (incorrect page-table walks and cross-mapping leakage within the kernel), not a VM escape or cross-authority boundary break.\nC:H - Stale non-leaf walk-cache entries after `pud_clear()` can cause incorrect page-table walks, enabling reads of memory that should be unmapped or mapped to different physical pages, constituting an arbitrary memory read primitive.\nI:H - Incorrect translations from stale PMD walk-cache entries can direct stores to unintended physical pages, and freed/reused page-table pages reached via stale cache entries provide a write/corruption primitive exploitable for control-flow hijacking.\nA:H - Stale walk-cache pointers to cleared or freed page-table structures can cause kernel faults, oops, or panics during page walks or concurrent GUP-fast access on the affected address space." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/arm64/include/asm/tlb.h" ], "versions": [ { "version": "6495204f8219a57859669d618b25d06176d5a872", "lessThan": "dced308d7d6a0de1c09d2058f38f1aaaf5cbb914", "status": "affected", "versionType": "git" }, { "version": "ce4cf24761467756462c0e1dbe4a5e9c9eb520fc", "lessThan": "47490bbb05c8c0e09cc3cfd237d8934ffc340583", "status": "affected", "versionType": "git" }, { "version": "daa6707b71a2da23a82979fa21f788aeb706f1a2", "lessThan": "0199c9d57861f17b556b6cba1f765c7cce79745b", "status": "affected", "versionType": "git" }, { "version": "ff37dd18ce7739a26aab0cc2d31006a45e6bde63", "lessThan": "d766a49d9b55705c4737cd8bb5d3faa2d31330fd", "status": "affected", "versionType": "git" }, { "version": "da06bb0ca45b1ca6f1ab55023e34e61a520337f3", "lessThan": "8ca7284da0e67b3e71d90ec17f08286774245ad9", "status": "affected", "versionType": "git" }, { "version": "9b671f6f432be07c0ddd66e437d6d0e0db684f83", "lessThan": "fe93e907b1af03cc229a80aa64a570a103d2b279", "status": "affected", "versionType": "git" }, { "version": "8ce720d5bd91e9dc16db3604aa4b1bf76770a9a1", "lessThan": "48125cd9c55cbe297b59fd1f9bda48b0960bd181", "status": "affected", "versionType": "git" }, { "version": "8ce720d5bd91e9dc16db3604aa4b1bf76770a9a1", "lessThan": "c2ff4764e03e7a8d758352f4aceb8fe1be6ac971", "status": "affected", "versionType": "git" }, { "version": "5.10.253", "lessThan": "5.10.259", "status": "affected", "versionType": "semver" }, { "version": "5.15.203", "lessThan": "5.15.210", "status": "affected", "versionType": "semver" }, { "version": "6.1.167", "lessThan": "6.1.176", "status": "affected", "versionType": "semver" }, { "version": "6.6.127", "lessThan": "6.6.143", "status": "affected", "versionType": "semver" }, { "version": "6.12.74", "lessThan": "6.12.93", "status": "affected", "versionType": "semver" }, { "version": "6.18.13", "lessThan": "6.18.35", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/arm64/include/asm/tlb.h" ], "versions": [ { "version": "6.19", "status": "affected" }, { "version": "0", "lessThan": "6.19", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.259", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.210", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.176", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.143", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.93", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.35", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.12", "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": "5.10.253", "versionEndExcluding": "5.10.259" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.203", "versionEndExcluding": "5.15.210" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.167", "versionEndExcluding": "6.1.176" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.127", "versionEndExcluding": "6.6.143" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.74", "versionEndExcluding": "6.12.93" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18.13", "versionEndExcluding": "6.18.35" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "7.0.12" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "7.1" } ] } ] } ], "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" } } } }