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vuln-cve/data/2026/89xxx/CVE-2026-89778.json
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{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2026-89778",
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"state": "PUBLISHED",
"assignerShortName": "Linux",
"dateReserved": "2026-09-11T19:38:34.765Z",
"datePublished": "2026-09-16T08:48:18.407Z",
"dateUpdated": "2026-10-19T08:52:30.510Z"
},
"containers": {
"cna": {
"providerMetadata": {
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux",
"dateUpdated": "2026-10-19T08:52:30.510Z"
},
"descriptions": [
{
"lang": "en",
"value": "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"
}
],
"metrics": [
{
"cvssV3_1": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"baseScore": 9.8,
"baseSeverity": "CRITICAL"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - isofs assigns s_export_op to isofs_export_ops; nfsd_read then nfsd_iter_read (vfs_iocb_iter_read) and ksmbd_vfs_read (kernel_read) perform VFS reads that reach generic_file_read_iter, filemap_read, and zisofs_read_folio, so a remote NFS or SMB client can trigger the bug on a host exporting a crafted ISO9660 image.\nAC:L - The attacker fully controls the Rock Ridge ZF parms (rock.c only rejects block_shift > 17) and the zisofs block pointer table; a block_shift below PAGE_SHIFT plus a nonempty sub-page block followed by an empty block (block_start==block_end) deterministically over-advances pages[] with no race.\nPR:N - A remote NFS or SMB client needs only read access to an exported iso9660 tree; AUTH_SYS media-server exports commonly require no host credentials, and compressed regular files default to S_IRUGO. No CAP_SYS_ADMIN on the victim host is required on the read path.\nUI:N - Once an iso9660 volume containing the crafted zisofs file is exported, the NFS or SMB server processes the client's READ automatically; no separate victim must open a file or click a dialog at attack time beyond that pre-existing export.\nS:U - The slab out-of-bounds pointer load and any memzero_page or SetPageUptodate side effects remain inside the host kernel; this is not a VM escape, IOMMU/DMA bypass, or other cross-authority boundary.\nC:H - zisofs_fill_pages loads an 8-byte pointer from one slot past a kmalloc-8 pages[] allocation and may treat adjacent heap data as a struct page. With heap grooming this memory corruption can be turned into a kernel information-disclosure primitive, so confidentiality impact is High.\nI:H - When the out-of-bounds pointer is non-NULL, memzero_page() writes zeros through kmap_local_page() of the forged page and SetPageUptodate() corrupts page flags, yielding a kernel write primitive against attacker-groomed heap or page objects that can be chained to control-flow hijack.\nA:H - KASAN reports a slab-out-of-bounds read in zisofs_read_folio; feeding a non-page pointer to kmap_local_page or memzero_page oopses or panics the kernel, and the attacker can repeat the NFS, SMB, or local read at will."
}
]
}
],
"affected": [
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"fs/isofs/compress.c"
],
"versions": [
{
"version": "59bc055211b8d266ab6089158058bf8268e02006",
"lessThan": "8b994ac5778a725982fd6a8a3afcaa068d4a93e3",
"status": "affected",
"versionType": "git"
},
{
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{
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"lessThan": "cd616aa0449a772a6956abf03358f0ff31720580",
"status": "affected",
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"lessThan": "9c6eace8d07e90f038c89eb3b756d65a7e259d48",
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{
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},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"fs/isofs/compress.c"
],
"versions": [
{
"version": "2.6.33",
"status": "affected"
},
{
"version": "0",
"lessThan": "2.6.33",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "5.15.221",
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.1.188",
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.6.157",
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.12.110",
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.18.52",
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "7.2.6",
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"operator": "OR",
"negate": false,
"cpeMatch": [
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"references": [
{
"url": "https://git.kernel.org/stable/c/8b994ac5778a725982fd6a8a3afcaa068d4a93e3"
},
{
"url": "https://git.kernel.org/stable/c/ad3249cdf9d4ba34bb8b1ff3956a4020fdfb5b0a"
},
{
"url": "https://git.kernel.org/stable/c/85904076cece72ee3194646ad7ac8e6659d999aa"
},
{
"url": "https://git.kernel.org/stable/c/f03425dcbe04aec3c27b9917e97d7d23a2908dda"
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{
"url": "https://git.kernel.org/stable/c/cd616aa0449a772a6956abf03358f0ff31720580"
},
{
"url": "https://git.kernel.org/stable/c/9c6eace8d07e90f038c89eb3b756d65a7e259d48"
},
{
"url": "https://git.kernel.org/stable/c/68d4d3e78150c7ed7d1195af63ad1e6ace30c661"
}
],
"title": "isofs: fix out-of-bounds page array access on empty zisofs block",
"x_generator": {
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}