# CVE-2026-89492

## Summary

- **CVE ID:** CVE-2026-89492
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** N/A
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 13, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:

ocfs2: validate directory-index entry counts when reading metadata

ocfs2_validate_dx_leaf() and ocfs2_validate_dx_root() check the ECC and
signature of an indexed-directory block before it reaches higher-level
callers, but neither validator bounds the ocfs2_dx_entry_list counts
against the capacity of the block that holds them.

ocfs2_dx_dir_search() then walks

	for (i = 0; i < le16_to_cpu(entry_list->de_num_used); i++)
		dx_entry = &entry_list->de_entries[i];

over de_num_used entries with no bounds check.  entry_list is either
dx_leaf->dl_list (from ocfs2_read_dx_leaf) or, for an inline root,
dx_root->dr_entries.  A crafted on-disk image can set de_num_used (and
de_count, which is the __counted_by_le() bound of de_entries) to 0xffff
and make the walk read far past the end of the 4KB metadata block, giving
a slab out-of-bounds read reachable from any path lookup, stat() or open()
on an indexed directory once the image is mounted.

Commit 775c17386a6f ("ocfs2: validate dx_root extent list fields during
block read") already bounds dr_list for the non-inline dx_root, but left
the inline dr_entries path and the dx_leaf dl_list unchecked.  Add the
same read-time validation for both entry lists: de_count must equal the
capacity of the block (ocfs2_dx_entries_per_leaf()/per_root()) and
de_num_used must not exceed de_count, rejecting corrupted metadata with
-EFSCORRUPTED before ocfs2_dx_dir_search() can walk an out-of-range entry
array.

de_count is always written as exactly the block capacity when a leaf or
inline root is formatted, so the equality check does not reject any valid
image.

Found by 0sec automated security-research tooling (https://0sec.ai).

## Affected Products

- Linux — Linux (9b7895efac906d66d19856194e1ba61f37e231a4)
- Linux — Linux (2.6.30)
- Linux — Linux (0)
- Linux — Linux (6.18.51)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)

## References

- [CNA](https://git.kernel.org/stable/c/fcfcba8fe17dbf2c8805690b8cc25e32d81249a4)
- [CNA](https://git.kernel.org/stable/c/b8a5c0c32df2c5b685ceef76ac77e37c7e1dc3ed)
- [CNA](https://git.kernel.org/stable/c/bc70726ddad53c7e9a9a85915bf2415b0d4f42f9)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.60%
- **EPSS Percentile:** 47.4

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._