CVE-2026-89490 Affecting linux-6.12 package, versions <6.12.111-1~deb12u1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIAN12-LINUX612-20506520
- published5 Oct 2026
- disclosed11 Sept 2026
Introduced: 11 Sep 2026
NewCVE-2026-89490 (opens in a new tab)How to fix?
Upgrade Debian:12 linux-6.12 to version 6.12.111-1~deb12u1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream linux-6.12 package and not the linux-6.12 package as distributed by Debian.
See How to fix? for Debian:12 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
ocfs2: fix readdir position truncation on 32-bit kernels
In ocfs2_dir_foreach_blk_el(), the directory cookie position is rebuilt with
ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1)) | offset;
ctx->pos is loff_t (signed 64-bit), while sb->s_blocksize is
unsigned long. On 32-bit kernels unsigned long is 32-bit, so the mask
~(sb->s_blocksize - 1)
is computed as a 32-bit unsigned value (e.g. 0xfffff000 for a 4 KiB
block size). In the AND expression with the 64-bit ctx->pos, that
unsigned operand is zero-extended to 64 bits per the usual arithmetic
conversions, yielding 0x00000000fffff000. The high 32 bits of
ctx->pos are silently cleared, even though directory size is
allowed to exceed 4 GiB.
When readdir() crosses the 4 GiB boundary on a 32-bit kernel the position is reset back into the first 4 GiB block, making the re-validation path re-enumerate already-returned dirents indefinitely.
This is ocfs2_dir_foreach_blk_el(), the extent-list readdir path taken for all non-inline directories, so a directory large enough to cross 4 GiB reaches it.
This is the same class of bug that commit 3dce5bb82c97 ("exfat: Fix bitwise operation having different size") fixed in exfat, and the fix mirrors the equivalent ext4 fix in this series. Cast the operand to loff_t so the mask is 64-bit before the AND:
ctx->pos = (ctx->pos & ~((loff_t)sb->s_blocksize - 1)) | offset;
64-bit kernels are unaffected.
References
- https://security-tracker.debian.org/tracker/CVE-2026-89490
- https://git.kernel.org/stable/c/1001fb3b69a11eaa0dc7c7428f6edfa48b88997a
- https://git.kernel.org/stable/c/a63308ab426f3a3c7e33b02c150ea59054620261
- https://git.kernel.org/stable/c/b53e2b271eeb6040c2a4a78230c570dc41cdcfa4
- https://git.kernel.org/stable/c/c0c165487a2ea5a37ddcdab4259157b7a527129c
- https://git.kernel.org/stable/c/1ae7029823ae4c91664cb32eec7fb8dd5e1a337a
- https://git.kernel.org/stable/c/94569154ba49f5f85645d2019c8e206213d8404e
- https://git.kernel.org/stable/c/c28dc3407937aa8f225942538cd585c9b28ea65a
- https://git.kernel.org/stable/c/f9dd5cad8d09110ddff2db1fe756aae93c7552ff