Bug 2532386 (CVE-2026-89653)

Summary: CVE-2026-89653 kernel: kernel: Memory corruption via out-of-bounds write in Ceph client
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Ceph file system client. When decoding metadata server maps (MDSMap), the client fails to properly validate rank identifiers within export targets against protocol limits. A malicious or compromised Ceph storage monitor can send a crafted map that triggers an out-of-bounds write to a stack buffer. This flaw can lead to kernel memory corruption or a system crash, resulting in a Denial of Service (DoS).
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description OSIDB Bzimport 2026-09-11 22:41:43 UTC 
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.