CVE-2026-43405

High

In the Linux kernel, the following vulnerability has been resolved: libceph: Use u32 for non-negative values in ceph_monmap_decode() This patch fixes unnecessary implicit conversions that change signedness of blob_len and num_mon in ceph_monmap_decode(). Currently blob_len and num_mon are (signed) int variables. They are used to hold values that are always non-negative and get assigned in ceph_decode_32_safe(), which is meant to assign u32 values. Both variables are subsequently used as unsigned values, and the value of num_mon is further assigned to monmap->num_mon, which is of type u32. Therefore, both variables should be of type u32. This is especially relevant for num_mon. If the value read from the incoming message is very large, it is interpreted as a negative value, and the check for num_mon > CEPH_MAX_MON does not catch it. This leads to the attempt to allocate a very large chunk of memory for monmap, which will most likely fail. In this case, an unnecessary attempt to allocate memory is performed, and -ENOMEM is returned instead of -EINVAL.

Package Linux Kernel
Published 2026-05-08
Last modified 2026-05-21
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

7.5

out of 10
High
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness type

CWE-908

CVE-2026-43405 is classified as CWE-908

See CWE-908 on MITRE CWE for full details on this weakness type.

Affected versions

Linux kernel versions 5.11 and later are affected. Fixed in 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.19, 6.19.9, 7.0 and their respective stable series.

Affected from
≥ 5.11
Fixed in
✓ 5.15.203 5.15.x ✓ 6.1.167 6.1.x ✓ 6.6.130 6.6.x ✓ 6.12.78 6.12.x ✓ 6.18.19 6.18.x ✓ 6.19.9 6.19.x ✓ 7.0

References

The following references provide additional information about CVE-2026-43405 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

7 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2026-43405?

    CVE-2026-43405 is a High severity Linux kernel vulnerability with a CVSS score of 7.5 out of 10 . It affects Linux kernel versions from 5.11 onward and has been patched in 5.15.203, 6.1.167, 6.6.130 and others. CVE-2026-43405 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-43405?

    CVE-2026-43405 has a CVSS score of 7.5 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H .

  • Is there a patch available for CVE-2026-43405?

    Yes — CVE-2026-43405 has been patched. Fixed versions include 5.15.203, 6.1.167, 6.6.130 and others. If you are running Linux kernel 5.11 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-43405 actively exploited?

    No — CVE-2026-43405 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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