# RLSA-2026:21556: kernel security update

RLSA-2026:21556, released May 30, 2026, fixes 19 CVEs in kernel (version 0:5.14.0-687.12.1.el9_8). None of them is reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/fix/linux/rlsa-2026-21556
- Platform: Linux
- Released: May 30, 2026
- Priority: High (Closes CVE-2026-23455, high severity)
- CVEs: 19, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://errata.rockylinux.org/RLSA-2026:21556

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [kernel](https://patchblox.com/security/data/product/linux/kernel.md) | rocky 9 | 0:5.14.0-687.12.1.el9_8 |

## CVEs this fix closes

| CVE | Priority | Title | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2026-23455](https://patchblox.com/security/data/cve/CVE-2026-23455.md) | High | kernel: In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: check for zero leng... | 9.1 | 0.0159 |  |
| [CVE-2026-31685](https://patchblox.com/security/data/cve/CVE-2026-31685.md) | High | netfilter: ip6t_eui64: reject invalid MAC header for all packets | 9.4 | 0.0049 |  |
| [CVE-2026-43158](https://patchblox.com/security/data/cve/CVE-2026-43158.md) | High | kernel-64kb: xfs: fix freemap adjustments when adding xattrs to leaf blocks (bsc#1264595). | 8.8 | 0.0047 |  |
| [CVE-2026-43190](https://patchblox.com/security/data/cve/CVE-2026-43190.md) | High | kernel: In the Linux kernel, the following vulnerability has been resolved: netfilter: xt_tcpmss: check remaining length befo... | 8.2 | 0.0046 |  |
| [CVE-2026-31709](https://patchblox.com/security/data/cve/CVE-2026-31709.md) | High | smb: client: validate the whole DACL before rewriting it in cifsacl | 8.8 | 0.0035 |  |
| [CVE-2026-31408](https://patchblox.com/security/data/cve/CVE-2026-31408.md) | High | Bluetooth: SCO: Fix use-after-free in sco_recv_frame() due to missing sock_hold | 8.8 | 0.0032 |  |
| [CVE-2026-43110](https://patchblox.com/security/data/cve/CVE-2026-43110.md) | High | kernel-default: wifi: brcmfmac: validate bsscfg indices in IF events (bsc#1264482). | 8.8 | 0.0027 |  |
| [CVE-2026-43051](https://patchblox.com/security/data/cve/CVE-2026-43051.md) | High | kernel-64kb: Security update for the Linux Kernel | 8.1 | 0.0026 |  |
| [CVE-2025-68366](https://patchblox.com/security/data/cve/CVE-2025-68366.md) | High | kernel-64kb: nbd: defer config unlock in nbd_genl_connect (bsc#1255622). | 8.8 | 0.0020 |  |
| [CVE-2025-38653](https://patchblox.com/security/data/cve/CVE-2025-38653.md) | High | proc: use the same treatment to check proc_lseek as ones for proc_read_iter et.al | 7.8 | 0.0018 |  |
| [CVE-2026-43303](https://patchblox.com/security/data/cve/CVE-2026-43303.md) | High | mm/page_alloc: clear page->private in free_pages_prepare() | 7.8 | 0.0017 |  |
| [CVE-2026-23392](https://patchblox.com/security/data/cve/CVE-2026-23392.md) | High | netfilter: nf_tables: release flowtable after rcu grace period on error | 8.8 | 0.0017 |  |
| [CVE-2025-71089](https://patchblox.com/security/data/cve/CVE-2025-71089.md) | High | iommu: disable SVA when CONFIG_X86 is set | 7.8 | 0.0016 |  |
| [CVE-2025-68183](https://patchblox.com/security/data/cve/CVE-2025-68183.md) | High | linux: In the Linux kernel, the following vulnerability has been resolved:  ima: don't clear IMA_DIGSIG flag when setting or... | 7.8 | 0.0015 |  |
| [CVE-2025-68724](https://patchblox.com/security/data/cve/CVE-2025-68724.md) | High | linux: In the Linux kernel, the following vulnerability has been resolved:  crypto: asymmetric_keys - prevent overflow in as... | 8.1 | 0.0014 |  |
| [CVE-2026-43027](https://patchblox.com/security/data/cve/CVE-2026-43027.md) | High | kernel-default: netfilter: nf_conntrack_helper: pass helper to expect cleanup (bsc#1263933). | 7.8 | 0.0013 |  |
| [CVE-2026-43020](https://patchblox.com/security/data/cve/CVE-2026-43020.md) | High | kernel-64kb: Security update for the Linux Kernel | 7.8 | 0.0013 |  |
| [CVE-2026-31684](https://patchblox.com/security/data/cve/CVE-2026-31684.md) | High | net: sched: act_csum: validate nested VLAN headers | 7.8 | 0.0012 |  |
| [CVE-2026-43023](https://patchblox.com/security/data/cve/CVE-2026-43023.md) | High | kernel-default: Bluetooth: SCO: fix race conditions in sco_sock_connect() (bsc#1264137). | 7.8 | 0.0010 |  |

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Data as of 2026-11-11T01:43:54Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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