---
id: CVE-2026-89984
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  perf/x86/intel: Fix kernel address leakages in LBR stack

  Before Arch LBR gained CPL filtering support, a user-only branch stack
  could still contain kernel addresses
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  perf/x86/intel: Fix kernel address leakages in LBR stack

  Before Arch LBR gained CPL filtering support, a user-only branch stack
  could still contain kernel addresses. A…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 47125db27e47e9d44c878bf8925aa057824bb0d5 <
    f3705db4e6378cc1b91a38ce0fe2f879055e23ca
  - >-
    Linux >= 47125db27e47e9d44c878bf8925aa057824bb0d5 <
    b589147f54adc62e4172e4acf079ad5fb7b3687f
  - >-
    Linux >= 47125db27e47e9d44c878bf8925aa057824bb0d5 <
    be0628a101ac05b085aaa4f650d48bd3915e80fa
  - >-
    Linux >= 47125db27e47e9d44c878bf8925aa057824bb0d5 <
    ca19a175e89b7de604fab736436cbab74030b47a
  - >-
    Linux >= 47125db27e47e9d44c878bf8925aa057824bb0d5 <
    6ac26161db27f7fb9d9e89ae240dbe52795496cc
  - >-
    Linux >= 47125db27e47e9d44c878bf8925aa057824bb0d5 <
    3c492c8eba02698ca893a9a13388d2adf6dfb839
  - >-
    Linux >= 47125db27e47e9d44c878bf8925aa057824bb0d5 <
    68c4b780b266a435261a1e029bede5ee3c2735cc
  - >-
    Linux >= 47125db27e47e9d44c878bf8925aa057824bb0d5 <
    e2b0575900ff72aa82748af96e7bd564ade5157a
  - Linux 5.9
published: '2026-09-16'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T11:17:09.403'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89984'
references:
  - url: 'https://git.kernel.org/stable/c/3c492c8eba02698ca893a9a13388d2adf6dfb839'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/68c4b780b266a435261a1e029bede5ee3c2735cc'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6ac26161db27f7fb9d9e89ae240dbe52795496cc'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b589147f54adc62e4172e4acf079ad5fb7b3687f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/be0628a101ac05b085aaa4f650d48bd3915e80fa'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ca19a175e89b7de604fab736436cbab74030b47a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e2b0575900ff72aa82748af96e7bd564ade5157a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f3705db4e6378cc1b91a38ce0fe2f879055e23ca'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-16T10:53:53.950Z'
epss: 0.00211
epssPercentile: 0.11608
---

## Overview

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

perf/x86/intel: Fix kernel address leakages in LBR stack

Before Arch LBR gained CPL filtering support, a user-only branch stack
could still contain kernel addresses. As a result, kernel branch records
may be exposed to user space even when PERF_SAMPLE_BRANCH_USER is
requested.

For example, on Intel Tiger Lake, the following command can still report
SYSRET/ERET entries with kernel-space from addresses:

$ ./perf record -e cycles:p -o - --branch-filter any,save_type,u -- \
 	./perf bench syscall basic --loop 1000 | \
	./perf script -i - --fields brstack|tr ' ' '\n'| \
	grep -E '0x[89a-f][0-9a-f]{15}'

    Total time: 0.000 [sec]

      0.219000 usecs/op
     4,566,210 ops/sec
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.551 MB - ]
0xffffffff93c001c8/0x7f12a2b1d647/P/-/-/16959/SYSRET/-
0xffffffff93c001c8/0x7f12a2b1d5c2/P/-/-/17535/SYSRET/-
0xffffffff93c01928/0x7f12a2861000/P/-/-/6719/ERET/-
0xffffffff93c01928/0x7f12a297a000/P/-/-/8575/ERET/-

The problem is that intel_pmu_lbr_filter() does not fully validate the
privilege level of sampled entries. It filters some mismatches based on
the branch type and the to address, but it does not reject entries whose
from address violates the requested branch privilege filter.

Fix this by extending software filtering to validate both from and to
addresses against br_sel. Any LBR entry contains kernel address does not
match the requested user filter is dropped. This prevents kernel
addresses from appearing in user-only branch stacks.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.