isofs: fix out-of-bounds page array access on empty zisofs block
In the Linux kernel, the following vulnerability has been resolved: isofs: fix out-of-bounds page array access on empty zisofs block zisofs_uncompress_block()'s empty-block fast path returns pcount << PAGE_SHIFT, ignoring the incoming poffset, unlike the decompression path which returns bytes produced relative to poffset. zisofs_fill_pages() uses that return to advance its page cursor, so when the zisofs block size is below PAGE_SIZE and a sub-page block leaves poffset partway into a page, a following empty block over-counts and advances pages[] one element past its end, after which "if (poffset && *pages)" reads pages[1] out of bounds. rock.c only rejects a block-size shift > 17, so a crafted "ZF" Rock Ridge record can set it below PAGE_SHIFT; the bug is reached by an ordinary read() of a compressed file on such a mounted ISO9660 image. Return the byte count relative to poffset and zero only [poffset, PAGE_SIZE) of the first page, matching the decompression path. The page-aligned case (poffset == 0) is unaffected. BUG: KASAN: slab-out-of-bounds in zisofs_read_folio (fs/isofs/compress.c:290) Read of size 8 at addr ffff88800f5eac48 by task exploit/142 zisofs_read_folio (fs/isofs/compress.c:290) read_pages (mm/readahead.c:184) ... filemap_read (mm/filemap.c:2814) vfs_read (fs/read_write.c:574) __x64_sys_pread64 (fs/read_write.c:769) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) The buggy address is located 0 bytes
CVE-2026-89778
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-89778
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "59bc055211b8d266ab6089158058bf8268e02006",
"lessThan": "8b994ac5778a725982fd6a8a3afcaa068d4a93e3",
"versionType": "git"
},
{
"status": "affected",
"version": "59bc055211b8d266ab6089158058bf8268e02006",
"lessThan": "ad3249cdf9d4ba34bb8b1ff3956a4020fdfb5b0a",
"versionType": "git"
},
{
"status": "affected",
"version": "59bc055211b8d266ab6089158058bf8268e02006",
"lessThan": "85904076cece72ee3194646ad7ac8e6659d999aa",
"versionType": "git"
},
{
"status": "affected",
"version": "59bc055211b8d266ab6089158058bf8268e02006",
"lessThan": "f03425dcbe04aec3c27b9917e97d7d23a2908dda",
"versionType": "git"
},
{
"status": "affected",
"version": "59bc055211b8d266ab6089158058bf8268e02006",
"lessThan": "cd616aa0449a772a6956abf03358f0ff31720580",
"versionType": "git"
},
{
"status": "affected",
"version": "59bc055211b8d266ab6089158058bf8268e02006",
"lessThan": "9c6eace8d07e90f038c89eb3b756d65a7e259d48",
"versionType": "git"
},
{
"status": "affected",
"version": "59bc055211b8d266ab6089158058bf8268e02006",
"lessThan": "68d4d3e78150c7ed7d1195af63ad1e6ace30c661",
"versionType": "git"
}
],
"programFiles": [
"fs/isofs/compress.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.33"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "2.6.33",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.15.221",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.188",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.157",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.110",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.52",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.6",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/isofs/compress.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-89778
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #35245 · Revision 1
- Added to Heist Feed
- Publisher date