CVE-2026-68159

A flaw was found in libceph in the Linux kernel. A remote attacker, acting as a malicious monitor, could send a specially crafted OSDMap (Object Storage Device Map) with an overly long pg_temp or pg_upmap entry. This could lead to a stack out-of-bounds write, resulting in a kernel bug and potentially a denial of service.

This vulnerability is rated as Important because a rogue or compromised Ceph monitor can induce stack corruption within the host operating system, potentially leading to privilege escalation or a kernel panic. Standard Red Hat Enterprise Linux installations do not load the Ceph network client drivers by default, significantly limiting ambient exposure. Systems are only vulnerable when configured to mount kernel CephFS filesystems or map RBD block storage devices across untrusted network boundaries.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

If the system does not require the libceph module for Ceph cluster connectivity, prevent the ceph kernel module from loading by blacklisting it. Create a file /etc/modprobe.d/ceph.conf with the content blacklist ceph. After creating the file, regenerate the initramfs using dracut -f -v and reboot the system for the changes to take effect. If libceph is in use, restrict network access to Ceph monitors to trusted hosts through firewall rules to reduce the attack surface.