Important: kernel security update

Open Source Vulnerabilities ALSA-2026:21556

The kernel packages contain the Linux kernel, the core of any Linux operating system. Security Fix(es): * kernel: proc: use the same treatment to check proc_lseek as ones for proc_read_iter et.al (CVE-2025-38653) * kernel: ima: don't clear IMA_DIGSIG flag when setting or removing non-IMA xattr (CVE-2025-68183) * kernel: nbd: defer config unlock in nbd_genl_connect (CVE-2025-68366) * kernel: crypto: asymmetric_keys - prevent overflow in asymmetric_key_generate_id (CVE-2025-68724) * kernel: iommu: disable SVA when CONFIG_X86 is set (CVE-2025-71089) * kernel: netfilter: nf_tables: release flowtable after rcu grace period on error (CVE-2026-23392) * kernel: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() (CVE-2026-23455) * kernel: Bluetooth: SCO: Fix use-after-free in sco_recv_frame() due to missing sock_hold (CVE-2026-31408) * kernel: net: sched: act_csum: validate nested VLAN headers (CVE-2026-31684) * kernel: netfilter: ip6t_eui64: reject invalid MAC header for all packets (CVE-2026-31685) * kernel: netfilter: nf_conntrack_helper: pass helper to expect cleanup (CVE-2026-43027) * kernel: Bluetooth: MGMT: validate LTK enc_size on load (CVE-2026-43020) * kernel: HID: wacom: fix out-of-bounds read in wacom_intuos_bt_irq (CVE-2026-43051) * kernel: smb: client: validate the whole DACL before rewriting it in cifsacl (CVE-2026-31709) * kernel: Bluetooth: SCO: fix race conditions in sco_sock_connect() (CVE-2026-43023) * kernel: wifi: brcmfmac: validate bsscfg indices in IF events (CVE-2026-43110) * kernel: netfilter: xt_tcpmss: check remaining length before reading optlen (CVE-2026-43190) * kernel: xfs: fix freemap adjustments when adding xattrs to leaf blocks (CVE-2026-43158) * kernel: mm/page_alloc: clear page->private in free_pages_prepare() (CVE-2026-43303) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.