{"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"}}}}