CVE-2026-89653 (CVSS 9.8)

Description

In the Linux kernel, the following vulnerability has been resolved: ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode MDSMap export_targets entries are monitor controlled. check_new_map() uses each entry as a bit number in a fixed stack bitmap, so a rank outside the protocol namespace can make set_bit() write past the end of the array. Reject ranks outside CEPH_MAX_MDS while decoding the map. Do not validate against possible_max_rank here because maps may legitimately reference ranks beyond a temporarily reduced max_mds.

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CVSS v3.1 Score

9.8

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0051

Probability of exploitation

0.42%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/3740c88ca9cb2210a8dbdd55ea4cec119fbe86fe https://git.kernel.org/stable/c/4d298880f82c42383b36946bafde7ccf4d804c9b https://git.kernel.org/stable/c/736adee11af36e407ed902264f8b2fb5cf94b62f https://git.kernel.org/stable/c/8c823bbab3c24e657469a84db96902ba82d4e8bb https://git.kernel.org/stable/c/96c3f5fbb0d5386e7111426f047f98cec4586674 https://git.kernel.org/stable/c/aedc9053d909508a5f56c3f49f885fc030df4730 https://git.kernel.org/stable/c/c4addccd05bacbef2144b4db14853d0308a218ac

Frequently Asked Questions

What is CVE-2026-89653? +

In the Linux kernel, the following vulnerability has been resolved: ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode MDSMap export_targets entries are monitor controlled. check_new_map() uses each entry as a bit number in a fixed stack bitmap, so a rank outside the protocol namespace can make set_bit() write past the end of the array. Reject ranks outside CEPH_MAX_MDS while decoding the map. Do not validate against possible_max_rank here because maps may legitimately reference ranks beyond a temporarily reduced max_mds. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-89653? +

CVE-2026-89653 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0051, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-89653? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

CVE-2026-89653