Medium [CVE-2026-68155] Linux kernel (libceph): Denial of Service due to malformed monitor maps
This medium-severity Red Hat Linux advisory covers CVE-2026-68155 affecting Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8.
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Summary
In the Linux kernel, the following vulnerability has been resolved: libceph: Reject monmaps advertising zero monitors A message of type CEPH_MSG_MON_MAP contains a monmap that is sent from a monitor to the client. This monmap contains information about the existing monitors in the cluster.
Currently, a monmap indicating that there are zero monitors in the cluster is treated as valid. Therefore, such a monmap must be corrupted and should be treated as invalid.
Furthermore, a monmap with a monitor count of zero can subsequently crash the client when attempting to open a session with a monitor in __open_session().
This happens because the "BUG_ON(monc->monmap->num_mon CEPH_MAX_MON. [ idryomov: drop "log output for unusual values of num_mon" part ] A remote attacker could send a specially crafted monitor map (monmap) that advertises zero monitors. This vulnerability results in a Denial of Service (DoS) for the client.
Red Hat severity: Important — CVSS 4.4 (CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-617.
Affected Red Hat products: Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat OpenShift Container Platform 4. Red Hat lists Red Hat Enterprise Linux 10; Red Hat Enterprise Linux for NVIDIA 26 as not affected.
Red Hat does not currently list a fixing RHSA for this CVE.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
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