CVE-2026-89655 Affecting kernel-livepatch-6_4_0-150700_53_90-default package, versions <1-150700.15.3.1


Severity

Recommended
0.0
medium
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.71% (53rd percentile)

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  • Snyk IDSNYK-SLES157-KERNELLIVEPATCH6401507005390DEFAULT-22233939
  • published5 Nov 2026
  • disclosed3 Nov 2026

Introduced: 3 Nov 2026

NewCVE-2026-89655  (opens in a new tab)

How to fix?

Upgrade SLES:15.7 kernel-livepatch-6_4_0-150700_53_90-default to version 1-150700.15.3.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-livepatch-6_4_0-150700_53_90-default package and not the kernel-livepatch-6_4_0-150700_53_90-default package as distributed by SLES. See How to fix? for SLES:15.7 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

ceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock

list_for_each_entry() iterates ci->i_cap_flush_list but drops i_ceph_lock to send cap messages. During the unlock window, handle_cap_flush_ack() can acquire i_ceph_lock, detach cf entries with tid <= flush_tid from the list, release i_ceph_lock, and free them via ceph_free_cap_flush() outside any lock. When the original thread reacquires i_ceph_lock and the for-loop macro advances via cf = list_next_entry(cf, i_list), it dereferences cf->i_list.next on freed memory.

The race timeline:

__kick_flushing_caps() handle_cap_flush_ack()


holds i_ceph_lock <--- iterates to cf (tid=10) prepares FLUSH message drops i_ceph_lock <--- __send_cap() ── FLUSH(tid=10) MDS sends FLUSH_ACK(tid=10) ---> acquires i_ceph_lock cf->tid(10) <= flush_tid(10), detaches cf from i_cap_flush_list drops i_ceph_lock ceph_free_cap_flush(cf) <- frees it! acquires i_ceph_lock <--- for-loop advances: cf = list_next_entry(cf, i_list) -- UAF on freed cf->i_list.next

The cf was just sent by __kick_flushing_caps itself via __send_cap(). The MDS may respond with FLUSH_ACK quickly enough that handle_cap_flush_ack() frees cf before __kick_flushing_caps can finish the iteration.

Fix by converting to a manual while loop: save the next pointer under i_ceph_lock before dropping it, then use the saved pointer after reacquiring, so the potentially-freed cf is never accessed again.

CVSS Base Scores

version 3.1