{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "471fbbea7ff7061b2d6474665cb5a2ceb4fd6500"
            },
            {
              "fixed": "4d20106c536b73c4a8a02652dc85e35898baebf7"
            },
            {
              "fixed": "61a395967de06edba58760e81907a272db749faa"
            },
            {
              "fixed": "e94676a08af6312aa72d8a981232b281f9bcfcf5"
            },
            {
              "fixed": "d8c184bec24b5a00ae96d704856d935eaded1685"
            },
            {
              "fixed": "3933884bc3102898b458c53fbd1ac52eb9cdb8a4"
            },
            {
              "fixed": "83663c0b739480c00cfe785675db87520ec484ed"
            },
            {
              "fixed": "c7e6b863d298f56522d0d08554bbea7f142e6588"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.13.0"
            },
            {
              "fixed": "5.15.221"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.188"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.157"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.110"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.52"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89787.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: check dir entry fits before reading the hash trailer in ext4_search_dir()\n\nFor casefolded encrypted directories ext4 stores an 8-byte hash trailer\nafter the name (EXT4_DIRENT_HASHES()), at an offset derived from\nde-\u003ename_len.  On the sb_no_casefold_compat_fallback() path ext4_match()\nreads that trailer, but ext4_search_dir()'s by-hand pre-check only tests\nde-\u003ename + de-\u003ename_len \u003c= dlimit, which proves the name fits, not the\nrounded trailer.  A crafted entry whose name ends at the block boundary\npasses the check while EXT4_DIRENT_HASHES(de) lands past the block end,\nso ext4_match() reads out of bounds on an ordinary lookup.  KASAN reports\nit as a use-after-free when the page after the directory block holds a\nfreed object:\n\n  BUG: KASAN: use-after-free in ext4_match (fs/ext4/namei.c:1435)\n  Read of size 4 at addr ffff888010458000 by task exploit\n  Call Trace:\n   ext4_match (fs/ext4/namei.c:1435)\n   ext4_search_dir (fs/ext4/namei.c:1470)\n   __ext4_find_entry (fs/ext4/namei.c:1268 fs/ext4/namei.c:1632)\n   ext4_lookup (fs/ext4/namei.c:1703 fs/ext4/namei.c:1769)\n   ...\n   filename_lookup (fs/namei.c:2842)\n   vfs_statx (fs/stat.c:353)\n   __do_sys_newfstatat (fs/stat.c:538)\n   do_syscall_64 (arch/x86/entry/syscall_64.c:94)\n   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)\n\nRequire, for hash-in-dirent directories, that the whole entry including\nthe rounded trailer fits before calling ext4_match().  This is the same\nbound ext4_check_dir_entry() already enforces via ext4_dir_rec_len(), so\nno well-formed entry is rejected.  The other caller, ext4_find_dest_de(),\nruns ext4_check_dir_entry() first and is unaffected.",
  "id": "CVE-2026-89787",
  "modified": "2026-09-18T03:31:06.097548936Z",
  "published": "2026-09-16T08:48:24.403Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3933884bc3102898b458c53fbd1ac52eb9cdb8a4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4d20106c536b73c4a8a02652dc85e35898baebf7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/61a395967de06edba58760e81907a272db749faa"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/83663c0b739480c00cfe785675db87520ec484ed"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c7e6b863d298f56522d0d08554bbea7f142e6588"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d8c184bec24b5a00ae96d704856d935eaded1685"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e94676a08af6312aa72d8a981232b281f9bcfcf5"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89787.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89787"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "ext4: check dir entry fits before reading the hash trailer in ext4_search_dir()"
}