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CVE-2026-43067

Critical Vulnerability: CVE-2026-43067 — linux — linux_kernel

In the Linux kernel, the following vulnerability has been resolved: ext4: handle wraparound when searching for blocks for indirect mapped blocks Commit 4865c768b563 ("ext4: always allocate blocks only from groups inode can use") restricts what blocks will be allocated for indirect block based files to block numbers that fit within 32-bit block numbers. However, when using a review bot running on the latest Gemini LLM to check this commit when backporting into an LTS based kernel, it raised th

Friday, October 16, 2026linuxVulnios Threat Intelligence
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Vulnerability Snapshot

CVE-2026-43067 is rated CRITICAL — exploitation is trivial or already observed in the wild and impact is severe. Patch immediately, not on the next maintenance window.

Affected technology: linux_kernel.

Executive Summary

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

ext4: handle wraparound when searching for blocks for indirect mapped blocks

Commit 4865c768b563 ("ext4: always allocate blocks only from groups

inode can use") restricts what blocks will be allocated for indirect

block based files to block numbers that fit within 32-bit block

numbers.

However, when using a review bot running on the latest Gemini LLM to

check this commit when backporting into an LTS based kernel, it raised

this concern:

If ac->ac_g_ex.fe_group is >= ngroups (for instance, if the goal

group was populated via stream allocation from s_mb_last_groups),

then start will be >= ngroups.

Does this allow allocating blocks beyond the 32-bit limit for

indirect block mapped files? The commit message mentions that

ext4_mb_scan_groups_linear() takes care to not select unsupported

groups. However, its loop uses group = *start, and the very first

iteration will call ext4_mb_scan_group() wit

Why It Matters

CVE-2026-43067 is rated CRITICAL severity, requiring immediate attention from security teams.

CVSS Base Score: 9.8/10

Affected Technologies

Vendors: linux

Products: linux_kernel

🛡️What Defenders Should Check

  • Check if you are affected — Review your asset inventory for products listed in CVE-2026-43067.
  • Apply available patches — Visit vendor advisories for the latest security updates.
  • Monitor for exploitation — Check your SIEM/IDS logs for related indicators.

    • Use Vulnios to continuously monitor your exposure to CVE-2026-43067 and similar vulnerabilities.

    References & Sources

  • https://git.kernel.org/stable/c/12624c5b724a81e14e532972b40d863b0de3b7d1
  • https://git.kernel.org/stable/c/2a368ccddfc492a0aa951e2caef2985f20e96503
  • https://git.kernel.org/stable/c/4bec4a498ce86314d470ae6144120461f2138c29
  • https://git.kernel.org/stable/c/83170a05908b6cf2fb3235d3065bf613ff866f3c
  • https://git.kernel.org/stable/c/bb81702370fad22c06ca12b6e1648754dbc37e0f
  • https://git.kernel.org/stable/c/f89bba144938921a2249237ad04a0183ff3f8930

    • How Vulnios Detects This

    Vulnios scans for this vulnerability using Trivy and Grype for CVE matching against your container images and OS package manifests. Run a scan against your environment to see whether you are exposed; findings are linked back to the original CVE record so triage starts with the patch path already known.

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    Affected Products

    linux_kernel

    Sources

    Related Threat Alerts

    Frequently Asked Questions

    What is CVE-2026-43067?

    CVE-2026-43067 is a critical-severity vulnerability tracked under the Common Vulnerabilities and Exposures program. In the Linux kernel, the following vulnerability has been resolved:

    ext4: handle wraparound when searching for blocks for indirect mapped blocks

    Commit 4865c768b563 ("ext4: always allocate blocks on

    Am I affected?

    Check whether your environment runs linux_kernel. If you operate any of those, treat yourself as in scope until you have evidence otherwise. A Vulnios scan will identify the exact assets carrying the affected version.

    How urgent is the response?

    Critical: do not wait for your normal patch cycle. Verify exposure today, apply the vendor patch immediately, and add detection rules for any post-exploit indicators.

    How do I remediate?

    Apply the vendor patch listed in the upstream advisory linked under Sources. If the patch is not yet available, follow the vendor-supplied workaround (often a config flag or feature disable) and add detections for the published exploit pattern in your SIEM. Re-scan after the patch lands to confirm the finding clears.

    Where can I track exploitation activity?

    Watch CISA's Known Exploited Vulnerabilities catalog for CVE-2026-43067. Cross-reference with public exploit databases and your own SIEM/IDS for indicator-of-compromise patterns. Vulnios tracks KEV status automatically and surfaces it on the asset findings view.

    How does Vulnios help with this?

    Vulnios continuously cross-references your asset inventory against the live CVE feed (NVD, vendor advisories, CISA KEV, and curated OSINT). When a new CVE matches your environment, you get a prioritized finding with the severity, KEV status, exploit-prediction (EPSS), and a direct path to the vendor patch. You can start a free scan from the homepage.

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