FKIE_CVE-2026-63875

Vulnerability from fkie_nvd - Published: 2026-07-19 16:17 - Updated: 2026-07-20 15:16
Severity
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: arm64: tlb: Flush walk cache when unsharing PMD tables When huge_pmd_unshare() is called to unshare a PMD table, the tlb_unshare_pmd_ptdesc() function sets tlb->unshared_tables=true but the aarch64 tlb_flush() only checked tlb->freed_tables to determine whether to use TLBF_NONE (vae1is, invalidates walk cache) or TLBF_NOWALKCACHE (vale1is, leaf-only). This caused the stale PMD page table entry to remain in the walk cache after unshare, potentially leading to incorrect page table walks. Fix by including unshared_tables in the check, so that when unsharing tables, TLBF_NONE is used and the walk cache is properly invalidated. Here is the detailed distinction between vae1is and vale1is: | Instruction Combination | Actual Invalidation Scope | | ------------------------ | --------------------------------------------------| | `VAE1IS` + TTL=`0` | All entries at all levels (full invalidation) | | `VAE1IS` + TTL=`2` (L2) | Non-leaf at Level 0/1 + leaf at Level 2 | | `VALE1IS` + TTL=`0` | Leaf entries at all levels (non-leaf not cleared) | | `VALE1IS` + TTL=`2` (L2) | Leaf entry at Level 2 only |
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0199c9d57861f17b556b6cba1f765c7cce79745b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/47490bbb05c8c0e09cc3cfd237d8934ffc340583
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/48125cd9c55cbe297b59fd1f9bda48b0960bd181
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8ca7284da0e67b3e71d90ec17f08286774245ad9
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c2ff4764e03e7a8d758352f4aceb8fe1be6ac971
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d766a49d9b55705c4737cd8bb5d3faa2d31330fd
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/dced308d7d6a0de1c09d2058f38f1aaaf5cbb914
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fe93e907b1af03cc229a80aa64a570a103d2b279
Impacted products
Vendor Product Version
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{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/include/asm/tlb.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "dced308d7d6a0de1c09d2058f38f1aaaf5cbb914",
              "status": "affected",
              "version": "6495204f8219a57859669d618b25d06176d5a872",
              "versionType": "git"
            },
            {
              "lessThan": "47490bbb05c8c0e09cc3cfd237d8934ffc340583",
              "status": "affected",
              "version": "ce4cf24761467756462c0e1dbe4a5e9c9eb520fc",
              "versionType": "git"
            },
            {
              "lessThan": "0199c9d57861f17b556b6cba1f765c7cce79745b",
              "status": "affected",
              "version": "daa6707b71a2da23a82979fa21f788aeb706f1a2",
              "versionType": "git"
            },
            {
              "lessThan": "d766a49d9b55705c4737cd8bb5d3faa2d31330fd",
              "status": "affected",
              "version": "ff37dd18ce7739a26aab0cc2d31006a45e6bde63",
              "versionType": "git"
            },
            {
              "lessThan": "8ca7284da0e67b3e71d90ec17f08286774245ad9",
              "status": "affected",
              "version": "da06bb0ca45b1ca6f1ab55023e34e61a520337f3",
              "versionType": "git"
            },
            {
              "lessThan": "fe93e907b1af03cc229a80aa64a570a103d2b279",
              "status": "affected",
              "version": "9b671f6f432be07c0ddd66e437d6d0e0db684f83",
              "versionType": "git"
            },
            {
              "lessThan": "48125cd9c55cbe297b59fd1f9bda48b0960bd181",
              "status": "affected",
              "version": "8ce720d5bd91e9dc16db3604aa4b1bf76770a9a1",
              "versionType": "git"
            },
            {
              "lessThan": "c2ff4764e03e7a8d758352f4aceb8fe1be6ac971",
              "status": "affected",
              "version": "8ce720d5bd91e9dc16db3604aa4b1bf76770a9a1",
              "versionType": "git"
            },
            {
              "lessThan": "5.10.259",
              "status": "affected",
              "version": "5.10.253",
              "versionType": "semver"
            },
            {
              "lessThan": "5.15.210",
              "status": "affected",
              "version": "5.15.203",
              "versionType": "semver"
            },
            {
              "lessThan": "6.1.176",
              "status": "affected",
              "version": "6.1.167",
              "versionType": "semver"
            },
            {
              "lessThan": "6.6.143",
              "status": "affected",
              "version": "6.6.127",
              "versionType": "semver"
            },
            {
              "lessThan": "6.12.93",
              "status": "affected",
              "version": "6.12.74",
              "versionType": "semver"
            },
            {
              "lessThan": "6.18.35",
              "status": "affected",
              "version": "6.18.13",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/include/asm/tlb.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.19"
            },
            {
              "lessThan": "6.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.259",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.210",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.176",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.93",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.35",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "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-\u003eunshared_tables=true\nbut the aarch64 tlb_flush() only checked tlb-\u003efreed_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                        |"
    }
  ],
  "id": "CVE-2026-63875",
  "lastModified": "2026-07-20T15:16:53.247",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-07-19T16:17:04.357",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0199c9d57861f17b556b6cba1f765c7cce79745b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/47490bbb05c8c0e09cc3cfd237d8934ffc340583"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/48125cd9c55cbe297b59fd1f9bda48b0960bd181"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8ca7284da0e67b3e71d90ec17f08286774245ad9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c2ff4764e03e7a8d758352f4aceb8fe1be6ac971"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d766a49d9b55705c4737cd8bb5d3faa2d31330fd"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/dced308d7d6a0de1c09d2058f38f1aaaf5cbb914"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fe93e907b1af03cc229a80aa64a570a103d2b279"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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