SB20260921198 - SUSE update for the Linux Kernel RT (Live Patch 18 for SUSE Linux Enterprise 15 SP7)
Published: September 21, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 6 vulnerabilities.
1) Use-after-free (CVE-ID: CVE-2026-64423)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a use-after-free in the IGMP multicast group handling in net/ipv4/igmp.c when destroying a device while concurrent RCU readers traverse the multicast hash table. A local user can trigger multicast group membership operations and concurrent network processing to cause a denial of service.
The issue occurs because multicast group entries can remain reachable through the device multicast hash table during RCU reclamation.
2) Use-after-free (CVE-ID: CVE-2026-64530)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a use-after-free in tcf_qevent_handle in net/sched/cls_api.c when handling TC_ACT_CONSUMED during qevent processing of fragmented traffic. A local user can send specially crafted fragmented network traffic to trigger use of an skb after ownership has been transferred and cause a denial of service.
Exploitation requires RED qdisc qevents together with ct defragmentation and traffic that produces out-of-order fragments.
3) Improper Initialization (CVE-ID: CVE-2026-64561)
CWE-ID: CWE-665 - Improper Initialization
CVSSv4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to improper state management in the KVM x86 shadow MMU page fault handling code when processing stale page faults after reclaiming shadow pages. A local user can trigger page faults that lead KVM to map memory into an invalid root to cause a denial of service.
The issue occurs when reclaiming shadow pages invalidates an in-use root, causing child shadow pages created during map or fetch operations to inherit an invalid role and violate the invariant that invalid shadow pages must not appear on the list of active MMU pages.
4) Use-after-free (CVE-ID: CVE-2026-64564)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a use-after-free in sctp_process_asconf_param() when processing crafted SCTP ASCONF DEL-IP parameters. A remote attacker can send a specially crafted SCTP ASCONF message to cause a denial of service.
The issue can occur when a single ASCONF carries DEL-IP parameters that free the cached transport and a later wildcard DEL-IP reuses the dangling transport pointer.
5) Race condition (CVE-ID: CVE-2026-64600)
CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CVSSv4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a race condition in xfs_reflink_fill_cow_hole and xfs_reflink_fill_delalloc in the XFS reflink code when processing direct I/O writes after cycling the ILOCK. A local user can trigger a racing direct I/O write operation to cause a denial of service.
The issue occurs because a stale data fork mapping can be used after the ILOCK is dropped and reacquired, which can result in incorrect shared-block state during copy-on-write handling.
6) Race condition (CVE-ID: CVE-2026-68138)
CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CVSSv4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a race condition leading to use-after-free and double-free in qdisc_get_rtab() and qdisc_put_rtab() when processing concurrent RTM_NEWTFILTER requests that add flower filters with a police action carrying the same rate. A local user can send concurrent netlink filter configuration requests to cause a denial of service.
The corrupted qdisc_rate_table object is shared system-wide because the affected rate-table list is process-global rather than per-network-namespace.
Remediation
Install update from vendor's website.