Unknown

CVE-2026-89984 — perf/x86/intel: Fix kernel address leakages in LBR stack

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.

Published Sep 16, 2026 · Updated Oct 19, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: Linux

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.2% (30-day exploitation probability)+2

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.21%

ahead of 11% of scored CVEs · Oct 19, 2026

Affects

Linux

CVSS base

—

Score not published yet.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Linux	Linux	≥ 47125db27e47e9d44c878bf8925aa057824bb0d5 and < f3705db4e6378cc1b91a38ce0fe2f879055e23ca≥ 47125db27e47e9d44c878bf8925aa057824bb0d5 and < b589147f54adc62e4172e4acf079ad5fb7b3687f≥ 47125db27e47e9d44c878bf8925aa057824bb0d5 and < be0628a101ac05b085aaa4f650d48bd3915e80fa≥ 47125db27e47e9d44c878bf8925aa057824bb0d5 and < ca19a175e89b7de604fab736436cbab74030b47a≥ 47125db27e47e9d44c878bf8925aa057824bb0d5 and < 6ac26161db27f7fb9d9e89ae240dbe52795496cc≥ 47125db27e47e9d44c878bf8925aa057824bb0d5 and < 3c492c8eba02698ca893a9a13388d2adf6dfb839≥ 47125db27e47e9d44c878bf8925aa057824bb0d5 and < 68c4b780b266a435261a1e029bede5ee3c2735cc≥ 47125db27e47e9d44c878bf8925aa057824bb0d5 and < e2b0575900ff72aa82748af96e7bd564ade5157a and 1 more version 5.9	Vulnerable	CVE Program (cve.org) e CISA ADP

EPSS over time FIRST

Oct 15, 2026 → Oct 19, 2026 · 4 reading(s) · max 0.21%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Not enough vector or weakness data: use the affected application’s logs as a starting point.

application logs

Timeline

What happened to this CVE, newest first.

2026
Record published
Oct 15, 2026
Affected products added · linux/linux
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Source status changed · → Received
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Sep 16, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

1× References added · Oct 19, 2026 – Oct 19, 2026
1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

10 on the record

git.kernel.org/stable/c/68c4b780b266a435261a1e029bede5ee3c2735cc
NIST National Vulnerability Database
git.kernel.org/stable/c/ca19a175e89b7de604fab736436cbab74030b47a
NIST National Vulnerability Database
git.kernel.org/stable/c/f3705db4e6378cc1b91a38ce0fe2f879055e23ca
NIST National Vulnerability Database
git.kernel.org/stable/c/3c492c8eba02698ca893a9a13388d2adf6dfb839
NIST National Vulnerability Database
github.com/advisories/GHSA-jjjc-8r8p-gw7x
GitHub Security Advisories
nvd.nist.gov/vuln/detail/CVE-2026-89984
GitHub Security Advisories
git.kernel.org/stable/c/e2b0575900ff72aa82748af96e7bd564ade5157a
NIST National Vulnerability Database
git.kernel.org/stable/c/be0628a101ac05b085aaa4f650d48bd3915e80fa
NIST National Vulnerability Database
git.kernel.org/stable/c/b589147f54adc62e4172e4acf079ad5fb7b3687f
NIST National Vulnerability Database
git.kernel.org/stable/c/6ac26161db27f7fb9d9e89ae240dbe52795496cc
NIST National Vulnerability Database

Elsewhere on this site

Linux
every CVE for this vendor

Related CVEs (same products)

Unknown CVE-2026-98866 sched/cache: Introduce task_struct->sched_cache_grp to fix UAF 1d
Unknown CVE-2026-98867 dm-pcache: bound the logical key offset from persistent memory 1d
Unknown CVE-2026-98868 dm-pcache: reject a kset that overruns its segment 1d
Unknown CVE-2026-98856 kprobes: Skip disarmed probes when checking optkprobe overlap 1d
Unknown CVE-2026-98857 ipvs: bound LBLCR and LBLC cache growth 1d
Unknown CVE-2026-98858 io_uring: fix task_work add use-after-free with SQPOLL 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No CVSS score published by NVD, the CNA, CISA or GitHub so far.
No fixed version, patch or mitigation documented.
No CISA SSVC assessment.
No CWE classification.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-89984 is "perf/x86/intel: Fix kernel address leakages in LBR stack", rated Unknown. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. EPSS 0.21% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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