CVE-2026-89653

ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode

CRITICAL
9.8
CVSS Score
Published: September 11, 2026 at 07:45 PM UTC
Updated: October 19, 2026 at 09:18 AM UTC
1 product affected across 1 vendorLinux Kernel

Using Linux by Linux?

Get instant alerts when new vulnerabilities affect Linux - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Severity
CRITICAL9.8
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

5.15d517b3983dd3106ca92d6c5d0d09415a4a09481c
Vendor states this is fixed in 3740c88ca9cb2210a8dbdd55ea4cec119fbe86fe (fixed)
Vendor states this is fixed in 4d298880f82c42383b36946bafde7ccf4d804c9b (fixed)
Vendor states this is fixed in 736adee11af36e407ed902264f8b2fb5cf94b62f (fixed)
Vendor states this is fixed in 8c823bbab3c24e657469a84db96902ba82d4e8bb (fixed)
Vendor states this is fixed in 96c3f5fbb0d5386e7111426f047f98cec4586674 (fixed)
Vendor states this is fixed in aedc9053d909508a5f56c3f49f885fc030df4730 (fixed)
Vendor states this is fixed in c4addccd05bacbef2144b4db14853d0308a218ac (fixed)
Vendor states this is fixed in 5.15 (unaffected)
Vendor states this is fixed in 5.15.221 (unaffected)
Vendor states this is fixed in 6.1.188 (unaffected)
Vendor states this is fixed in 6.12.109 (unaffected)
Vendor states this is fixed in 6.18.50 (unaffected)
Vendor states this is fixed in 6.6.157 (unaffected)
Vendor states this is fixed in 7.2.4 (unaffected)
Vendor states this is fixed in 7.3 (unaffected)
Vendor states this is fixed in 7.3-rc1 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitAutomatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

9.8CRITICALLinux
Vector?

Quick Info

StatusRECEIVED

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Free plan, no card