What’s Vulnerable › Vulnerabilities

CVE-2026-89653: ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-11 · updated 2026-10-19

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.

Affected products

• Linux kernel: 5.15 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux kernel 7.3. Check the vendor advisory for mitigations.

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

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