{"id":"CVE-2026-89778","published":"2026-09-16T09:17:08.253","lastModified":"2026-09-16T15:18:07.167","description":"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 << 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 && *pages)\" reads pages[1] out of bounds.  rock.c only\nrejects a block-size shift > 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","cvssScore":9.8,"cvssSeverity":"CRITICAL","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/68d4d3e78150c7ed7d1195af63ad1e6ace30c661","tags":[]},{"url":"https://git.kernel.org/stable/c/85904076cece72ee3194646ad7ac8e6659d999aa","tags":[]},{"url":"https://git.kernel.org/stable/c/8b994ac5778a725982fd6a8a3afcaa068d4a93e3","tags":[]},{"url":"https://git.kernel.org/stable/c/9c6eace8d07e90f038c89eb3b756d65a7e259d48","tags":[]},{"url":"https://git.kernel.org/stable/c/ad3249cdf9d4ba34bb8b1ff3956a4020fdfb5b0a","tags":[]},{"url":"https://git.kernel.org/stable/c/cd616aa0449a772a6956abf03358f0ff31720580","tags":[]},{"url":"https://git.kernel.org/stable/c/f03425dcbe04aec3c27b9917e97d7d23a2908dda","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":{"summary":"The flaw involves an out-of-bounds page array access in the Linux kernel's isofs module, specifically in the handling of empty zisofs blocks. This can lead to a kernel crash or potentially arbitrary code execution if an attacker can craft a malicious ISO9660 image.","exploitability":"Exploitation requires a crafted 'ZF' Rock Ridge record to set the block size below PAGE_SHIFT, and an ordinary read() of a compressed file on such an image. The exploit is moderately complex and requires specific conditions to be met.","blast_radius":"If exploited, the vulnerability could allow an attacker to execute arbitrary code with kernel privileges, leading to full system compromise.","remediation":"Upgrade to the fixed version 5.10.100 or later.","detection":"No reliable host or network indicator is derivable from the published description.","tags":["kernel","oom","compression","iso9660"],"model":"qwen2.5:7b-instruct","analyzedAt":"2026-09-28T08:59:39.000Z"}}