{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "59bc055211b8d266ab6089158058bf8268e02006"
            },
            {
              "fixed": "8b994ac5778a725982fd6a8a3afcaa068d4a93e3"
            },
            {
              "fixed": "ad3249cdf9d4ba34bb8b1ff3956a4020fdfb5b0a"
            },
            {
              "fixed": "85904076cece72ee3194646ad7ac8e6659d999aa"
            },
            {
              "fixed": "f03425dcbe04aec3c27b9917e97d7d23a2908dda"
            },
            {
              "fixed": "cd616aa0449a772a6956abf03358f0ff31720580"
            },
            {
              "fixed": "9c6eace8d07e90f038c89eb3b756d65a7e259d48"
            },
            {
              "fixed": "68d4d3e78150c7ed7d1195af63ad1e6ace30c661"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.6.33"
            },
            {
              "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-2026-89778.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nisofs: fix out-of-bounds page array access on empty zisofs block\n\nzisofs_uncompress_block()'s empty-block fast path returns\npcount \u003c\u003c PAGE_SHIFT, ignoring the incoming poffset, unlike the\ndecompression path which returns bytes produced relative to poffset.\nzisofs_fill_pages() uses that return to advance its page cursor, so when\nthe zisofs block size is below PAGE_SIZE and a sub-page block leaves\npoffset partway into a page, a following empty block over-counts and\nadvances pages[] one element past its end, after which\n\"if (poffset \u0026\u0026 *pages)\" reads pages[1] out of bounds.  rock.c only\nrejects a block-size shift \u003e 17, so a crafted \"ZF\" Rock Ridge record can\nset it below PAGE_SHIFT; the bug is reached by an ordinary read() of a\ncompressed file on such a mounted ISO9660 image.\n\nReturn the byte count relative to poffset and zero only\n[poffset, PAGE_SIZE) of the first page, matching the decompression path.\nThe page-aligned case (poffset == 0) is unaffected.\n\n  BUG: KASAN: slab-out-of-bounds in zisofs_read_folio (fs/isofs/compress.c:290)\n  Read of size 8 at addr ffff88800f5eac48 by task exploit/142\n   zisofs_read_folio (fs/isofs/compress.c:290)\n   read_pages (mm/readahead.c:184)\n   ...\n   filemap_read (mm/filemap.c:2814)\n   vfs_read (fs/read_write.c:574)\n   __x64_sys_pread64 (fs/read_write.c:769)\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  The buggy address is located 0 bytes to the right of the\n  allocated 8-byte region in the kmalloc-8 cache",
  "id": "CVE-2026-89778",
  "modified": "2026-09-18T03:30:43.940621795Z",
  "published": "2026-09-16T08:48:18.407Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/68d4d3e78150c7ed7d1195af63ad1e6ace30c661"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/85904076cece72ee3194646ad7ac8e6659d999aa"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8b994ac5778a725982fd6a8a3afcaa068d4a93e3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9c6eace8d07e90f038c89eb3b756d65a7e259d48"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ad3249cdf9d4ba34bb8b1ff3956a4020fdfb5b0a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cd616aa0449a772a6956abf03358f0ff31720580"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f03425dcbe04aec3c27b9917e97d7d23a2908dda"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89778.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89778"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "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": "isofs: fix out-of-bounds page array access on empty zisofs block"
}