{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "ca06197382bde0a3bc20215595d1c9ce20c6e341"
            },
            {
              "fixed": "e6f1a11cfb808441a43ffae9b476cc135732cd27"
            },
            {
              "fixed": "e48f413c2815787b8cade2795e194e3c4cd782ef"
            },
            {
              "fixed": "06c4e1e9967d332ac33ba38b7819851089ff9359"
            },
            {
              "fixed": "8e0abc17fbd7e305802e84fe98b4950d50f9c433"
            },
            {
              "fixed": "4d101016d5e587f820b3ae2d5bb6770d86342649"
            },
            {
              "fixed": "adfacfbaeae2cb760f492357cc36b41f84ef7f86"
            },
            {
              "fixed": "708b97e792945d3e4653939fd3405d71a61ad065"
            },
            {
              "fixed": "3f5f8ee9917cc2b9076ac533492d8a200edcabb8"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.7.0"
            },
            {
              "fixed": "5.10.260"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.211"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.177"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.144"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.95"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.38"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.1.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63808.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nexfat: fix potential use-after-free in exfat_find_dir_entry()\n\nIn exfat_find_dir_entry(), the buffer_head obtained from\nexfat_get_dentry() is released with brelse(bh) before the fall-through\nTYPE_EXTEND branch reads the directory entry through ep (which points\ninto bh-\u003eb_data):\n\n\tbrelse(bh);\n\tif (entry_type == TYPE_EXTEND) {\n\t\t...\n\t\tlen = exfat_extract_uni_name(ep, entry_uniname);\n\t\t...\n\t}\n\nAfter brelse() drops our reference, nothing guarantees that the\nunderlying page backing bh-\u003eb_data remains valid for the subsequent\nexfat_extract_uni_name() read. This is the same pattern fixed in\ncommit fc961522ddbd (\"exfat: Fix potential use after free in\nexfat_load_upcase_table()\").\n\nMove brelse(bh) so it runs after ep is no longer dereferenced on\neach branch.\n\nConfirmed on QEMU x86_64 with CONFIG_KASAN=y + CONFIG_DEBUG_PAGEALLOC=y\n+ CONFIG_PAGE_POISONING=y on linux-next, using a crafted exFAT image\n(long filename with same-hash collisions forcing the TYPE_EXTEND path).\nWith a debug-only invalidate_bdev() inserted between brelse(bh) and\nthe ep read to make the stale-deref window deterministic, the\nunpatched kernel faults:\n\n  BUG: KASAN: use-after-free in exfat_find_dir_entry+0x133b/0x15a0\n  BUG: unable to handle page fault for address: ffff88801a5fa0c2\n  Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI\n  RIP: 0010:exfat_find_dir_entry+0x1188/0x15a0\n\nWith this patch applied, the same instrumented harness completes\ncleanly under the same sanitizer stack. I have not reproduced a\ncrash on an uninstrumented kernel under ordinary reclaim; the\ninstrumented A/B establishes the lifetime violation and that the\npatch closes it, not an unaided triggerability claim.",
  "id": "CVE-2026-63808",
  "modified": "2026-07-22T05:30:03.634108748Z",
  "published": "2026-07-19T12:02:11.323Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/06c4e1e9967d332ac33ba38b7819851089ff9359"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3f5f8ee9917cc2b9076ac533492d8a200edcabb8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4d101016d5e587f820b3ae2d5bb6770d86342649"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/708b97e792945d3e4653939fd3405d71a61ad065"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8e0abc17fbd7e305802e84fe98b4950d50f9c433"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/adfacfbaeae2cb760f492357cc36b41f84ef7f86"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e48f413c2815787b8cade2795e194e3c4cd782ef"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e6f1a11cfb808441a43ffae9b476cc135732cd27"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63808.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63808"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "exfat: fix potential use-after-free in exfat_find_dir_entry()"
}