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CVE-2026-43407

Critical Vulnerability: CVE-2026-43407

In the Linux kernel, the following vulnerability has been resolved: libceph: Fix potential out-of-bounds access in ceph_handle_auth_reply() This patch fixes an out-of-bounds access in ceph_handle_auth_reply() that can be triggered by a message of type CEPH_MSG_AUTH_REPLY. In ceph_handle_auth_reply(), the value of the payload_len field of such a message is stored in a variable of type int. A value greater than INT_MAX leads to an integer overflow and is interpreted as a negative value. This lea

Wednesday, May 13, 2026Vulnios Threat Intelligence
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Vulnerability Snapshot

CVE-2026-43407 is rated CRITICAL — exploitation is trivial or already observed in the wild and impact is severe. Patch immediately, not on the next maintenance window.

Executive Summary

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

libceph: Fix potential out-of-bounds access in ceph_handle_auth_reply()

This patch fixes an out-of-bounds access in ceph_handle_auth_reply()

that can be triggered by a message of type CEPH_MSG_AUTH_REPLY. In

ceph_handle_auth_reply(), the value of the payload_len field of such a

message is stored in a variable of type int. A value greater than

INT_MAX leads to an integer overflow and is interpreted as a negative

value. This leads to decrementing the pointer address by this value and

subsequently accessing it because ceph_decode_need() only checks that

the memory access does not exceed the end address of the allocation.

This patch fixes the issue by changing the data type of payload_len to

u32. Additionally, the data type of result_msg_len is changed to u32,

as it is also a variable holding a non-negative length.

Also, an additional layer of sanity checks is introduced, ensuring that

directly after reading it from th

Why It Matters

CVE-2026-43407 is rated CRITICAL severity, requiring immediate attention from security teams.

CVSS Base Score: 9.1/10

🛡️What Defenders Should Check

  • Check if you are affected — Review your asset inventory for products listed in CVE-2026-43407.
  • 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-2026-43407 and similar vulnerabilities.

    References & Sources

  • https://git.kernel.org/stable/c/6cee34d6669fe176b4259131adb1a145c939b472
  • https://git.kernel.org/stable/c/8bb87547e92dcf0928ed763c60e0ac8d733c3656
  • https://git.kernel.org/stable/c/9f9e2297f45fc2d2524eb104c289d69ddef95665
  • https://git.kernel.org/stable/c/b282c43ed156ae15ea76748fc15cd5c39dc9ab72
  • https://git.kernel.org/stable/c/ea080b21092590122c3f971cf588932cdbf47847
  • https://git.kernel.org/stable/c/ed024d2f4c79c0eb2464df0fb640610ac301f9a0
  • https://git.kernel.org/stable/c/edc678e5cd11730a2834b43071d8923f05bc334d
  • https://git.kernel.org/stable/c/f9da5c1bbac5c8e33259fe00ed7347438fffa969

    • How Vulnios Detects This

    Vulnios scans for this vulnerability using Trivy and Grype for SBOM-based CVE matching and Vulnios CVE feed continuous monitoring against your asset inventory. 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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    Sources

    Related Threat Alerts

    Frequently Asked Questions

    What is CVE-2026-43407?

    CVE-2026-43407 is a critical-severity vulnerability tracked under the Common Vulnerabilities and Exposures program. In the Linux kernel, the following vulnerability has been resolved:

    libceph: Fix potential out-of-bounds access in ceph_handle_auth_reply()

    This patch fixes an out-of-bounds access in ceph_handle_au

    Am I affected?

    Affected technology is listed in the Affected Products section above. If your asset inventory contains any of them, assume in-scope until you can prove otherwise.

    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-2026-43407. 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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