FKIE_CVE-2026-63802

Vulnerability from fkie_nvd - Published: 2026-07-19 12:16 - 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: blk-cgroup: fix UAF in __blkcg_rstat_flush() When multiple blkgs in the same blkcg are released concurrently, a use-after-free can occur. The race happens when one blkg's __blkcg_rstat_flush() removes another blkg's iostat entries via llist_del_all(). The second blkg sees an empty list and proceeds to free itself while the first is still iterating over its entries. Move the flush from __blkg_release() (RCU callback) to blkg_release() (before call_rcu). This ensures the RCU grace period waits for any concurrent flush's rcu_read_lock() section to complete before freeing.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0ab5ee5a1badb58cbb2242617cb01a4972b1f2a2
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5e5b7f2ef854936e95dceb6a2fdfefcb7152d2c6
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/96e545410c4f74c89d496c1d5d9ef8d08f14368b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/afebe44facc48a61761e885bbb7f0380d4a603ec
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/bbebd9425cad3573d1527441753899b926525a0f
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "block/blk-cgroup.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "96e545410c4f74c89d496c1d5d9ef8d08f14368b",
              "status": "affected",
              "version": "20cb1c2fb7568a6054c55defe044311397e01ddb",
              "versionType": "git"
            },
            {
              "lessThan": "bbebd9425cad3573d1527441753899b926525a0f",
              "status": "affected",
              "version": "20cb1c2fb7568a6054c55defe044311397e01ddb",
              "versionType": "git"
            },
            {
              "lessThan": "5e5b7f2ef854936e95dceb6a2fdfefcb7152d2c6",
              "status": "affected",
              "version": "20cb1c2fb7568a6054c55defe044311397e01ddb",
              "versionType": "git"
            },
            {
              "lessThan": "afebe44facc48a61761e885bbb7f0380d4a603ec",
              "status": "affected",
              "version": "20cb1c2fb7568a6054c55defe044311397e01ddb",
              "versionType": "git"
            },
            {
              "lessThan": "0ab5ee5a1badb58cbb2242617cb01a4972b1f2a2",
              "status": "affected",
              "version": "20cb1c2fb7568a6054c55defe044311397e01ddb",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "0f6090d90f627d8c58f939067d6c6821ce1b3c68",
              "versionType": "git"
            },
            {
              "lessThan": "6.4",
              "status": "affected",
              "version": "6.3.9",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "block/blk-cgroup.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.4"
            },
            {
              "lessThan": "6.4",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.144",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.95",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.38",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2-rc1",
              "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\nblk-cgroup: fix UAF in __blkcg_rstat_flush()\n\nWhen multiple blkgs in the same blkcg are released concurrently,\na use-after-free can occur. The race happens when one blkg\u0027s\n__blkcg_rstat_flush() removes another blkg\u0027s iostat entries via\nllist_del_all(). The second blkg sees an empty list and proceeds\nto free itself while the first is still iterating over its entries.\n\nMove the flush from __blkg_release() (RCU callback) to blkg_release()\n(before call_rcu). This ensures the RCU grace period waits for any\nconcurrent flush\u0027s rcu_read_lock() section to complete before freeing."
    }
  ],
  "id": "CVE-2026-63802",
  "lastModified": "2026-07-20T15:16:47.013",
  "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": "2026-07-19T12:16:52.847",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0ab5ee5a1badb58cbb2242617cb01a4972b1f2a2"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5e5b7f2ef854936e95dceb6a2fdfefcb7152d2c6"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/96e545410c4f74c89d496c1d5d9ef8d08f14368b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/afebe44facc48a61761e885bbb7f0380d4a603ec"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/bbebd9425cad3573d1527441753899b926525a0f"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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