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

perf/x86/amd/brs: Fix kernel address leakage

A user-only branch stack can contain branches that originate from
the kernel. As a result, kernel addresses are exposed to user space
even when PERF_SAMPLE_BRANCH_USER is requested. On AMD processors
supporting X86_FEATURE_BRS (Zen 3 only), perf can still report entries
such as SYSRET/interrupt returns for which the branch-from addresses
are in the kernel.

E.g.

$ perf record -j any,u -c 4000 -e branch-brs -o - -- \
perf bench syscall basic --loop 1000 | \
perf script -i - -F brstack|tr ' ' '\n'| \
grep -E '0x[89a-f][0-9a-f]{15}'

...
0xffffffff810001c4/0x72e2e32955eb/-/-/-/0//-
0xffffffff810001c4/0x72e2d94a9821/-/-/-/0//-
0xffffffff810001c4/0x72e2d94ffa1b/-/-/-/0//-
...

BRS provides no hardware branch filtering, so privilege level
filtering is performed entirely in software. However, amd_brs_match_plm()
only validates the branch-to address against the requested privilege
levels. For branches from the kernel to user space, the branch-from
address is left unchecked and is leaked. Extend the software filter to
also validate the branch-from address, so that any branch record whose
branch-from address is in the kernel is dropped when
PERF_SAMPLE_BRANCH_USER is requested.

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History

Sat, 15 Aug 2026 10:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-200
CWE-284

Sat, 15 Aug 2026 06:00:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: perf/x86/amd/brs: Fix kernel address leakage A user-only branch stack can contain branches that originate from the kernel. As a result, kernel addresses are exposed to user space even when PERF_SAMPLE_BRANCH_USER is requested. On AMD processors supporting X86_FEATURE_BRS (Zen 3 only), perf can still report entries such as SYSRET/interrupt returns for which the branch-from addresses are in the kernel. E.g. $ perf record -j any,u -c 4000 -e branch-brs -o - -- \ perf bench syscall basic --loop 1000 | \ perf script -i - -F brstack|tr ' ' '\n'| \ grep -E '0x[89a-f][0-9a-f]{15}' ... 0xffffffff810001c4/0x72e2e32955eb/-/-/-/0//- 0xffffffff810001c4/0x72e2d94a9821/-/-/-/0//- 0xffffffff810001c4/0x72e2d94ffa1b/-/-/-/0//- ... BRS provides no hardware branch filtering, so privilege level filtering is performed entirely in software. However, amd_brs_match_plm() only validates the branch-to address against the requested privilege levels. For branches from the kernel to user space, the branch-from address is left unchecked and is leaked. Extend the software filter to also validate the branch-from address, so that any branch record whose branch-from address is in the kernel is dropped when PERF_SAMPLE_BRANCH_USER is requested.
Title perf/x86/amd/brs: Fix kernel address leakage
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-08-15T05:54:26.685Z

Reserved: 2026-08-09T03:40:39.914Z

Link: CVE-2026-72237

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-15T06:21:50.733

Modified: 2026-08-15T06:21:50.733

Link: CVE-2026-72237

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-15T17:30:11Z

Weaknesses