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VulnerabilityPublished Updated

CVE-2026-89492: Linux kernel · ocfs2: validate directory-index entry counts when reading metadata

Affects Linux kernelSource GCVE Database

0
Authoritative record:CVE-2026-89492· Critical 9.8

Not known to be exploited · CVSS 9.8 Critical.

Data as of 28 Oct 2026, 01:01 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 11 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-5.5 – 7.0.0-38.38
23 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1002.2 – 7.0.0-1014.14
15 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1003.3 – 7.0.0-1017.17
15 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threatsAffected
  • 7.0.0-1003.3 – 7.0.0-1016.16
9 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1002.2 – 7.0.0-1014.14
13 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threatsAffected
  • 7.0.0-1002.3 – 7.0.0-1008.9
6 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

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).

References

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