CVE-2026-89778isofs: fix out-of-bounds page array access on empty zisofs block
- 9.8CriticalCVSS base score
- 0.70%Exploitation in 30 daysEPSS · top 46% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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 to the right of the allocated 8-byte region in the kmalloc-8 cache
Timeline
ID reserved
By Linux
- 5 days later
· 5 days later
Published
- 33 days later
· 33 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Received | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.70% · top 46% of all CVEs (14 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.8.
Affected products
- affected 59bc055211b8d266ab6089158058bf8268e02006 – < 8b994ac5778a725982fd6a8a3afcaa068d4a93e3
- affected 59bc055211b8d266ab6089158058bf8268e02006 – < ad3249cdf9d4ba34bb8b1ff3956a4020fdfb5b0a
- affected 59bc055211b8d266ab6089158058bf8268e02006 – < 85904076cece72ee3194646ad7ac8e6659d999aa
- affected 59bc055211b8d266ab6089158058bf8268e02006 – < f03425dcbe04aec3c27b9917e97d7d23a2908dda
- affected 59bc055211b8d266ab6089158058bf8268e02006 – < cd616aa0449a772a6956abf03358f0ff31720580
- affected 59bc055211b8d266ab6089158058bf8268e02006 – < 9c6eace8d07e90f038c89eb3b756d65a7e259d48
- affected 59bc055211b8d266ab6089158058bf8268e02006 – < 68d4d3e78150c7ed7d1195af63ad1e6ace30c661
- affected 2.6.33
- unaffected < 2.6.33
- unaffected 5.15.221 – ≤ 5.15.*
- unaffected 6.1.188 – ≤ 6.1.*
- unaffected 6.6.157 – ≤ 6.6.*
- unaffected 6.12.110 – ≤ 6.12.*
- unaffected 6.18.52 – ≤ 6.18.*
- unaffected 7.2.6 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References7
- https://git.kernel.org/stable/c/8b994ac5778a725982fd6a8a3afcaa068d4a93e3 (opens in a new tab)
- https://git.kernel.org/stable/c/ad3249cdf9d4ba34bb8b1ff3956a4020fdfb5b0a (opens in a new tab)
- https://git.kernel.org/stable/c/85904076cece72ee3194646ad7ac8e6659d999aa (opens in a new tab)
- https://git.kernel.org/stable/c/f03425dcbe04aec3c27b9917e97d7d23a2908dda (opens in a new tab)
- https://git.kernel.org/stable/c/cd616aa0449a772a6956abf03358f0ff31720580 (opens in a new tab)
- https://git.kernel.org/stable/c/9c6eace8d07e90f038c89eb3b756d65a7e259d48 (opens in a new tab)
- https://git.kernel.org/stable/c/68d4d3e78150c7ed7d1195af63ad1e6ace30c661 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-80299 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-89778)Record last updated .