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Fencer Vulns
high 7.8

CVE-2025-38563 json

perf/core: Prevent VMA split of buffer mappings

published 2025-08-19 14 mo ago modified 2026-11-05 3 d ago also EUVD-2025-26105

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 34%
public exploits
0
none known

Summary

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

perf/core: Prevent VMA split of buffer mappings

The perf mmap code is careful about mmap()'ing the user page with the ringbuffer and additionally the auxiliary buffer, when the event supports it. Once the first mapping is established, subsequent mapping have to use the same offset and the same size in both cases. The reference counting for the ringbuffer and the auxiliary buffer depends on this being correct.

Though perf does not prevent that a related mapping is split via mmap(2), munmap(2) or mremap(2). A split of a VMA results in perf_mmap_open() calls, which take reference counts, but then the subsequent perf_mmap_close() calls are not longer fulfilling the offset and size checks. This leads to reference count leaks.

As perf already has the requirement for subsequent mappings to match the initial mapping, the obvious consequence is that VMA splits, caused by resizing of a mapping or partial unmapping, have to be prevented.

Implement the vm_operations_struct::may_split() callback and return unconditionally -EINVAL.

That ensures that the mapping offsets and sizes cannot be changed after the fact. Remapping to a different fixed address with the same size is still possible as it takes the references for the new mapping and drops those of the old mapping.

Patch / fix

  • Linux Linux 5.4.297, 5.10.241, 5.15.190, 6.1.148, 6.6.102, 6.12.42, 6.15.10, 6.16.1, 6.17
  • linux Debian 12 6.1.148-1
  • linux Debian 13 6.12.43-1
  • linux Debian 14 6.16.3-1

debian advisories DEBIAN-CVE-2025-38563

  • linux Ubuntu 22.04 LTS 5.15.0-163.173
  • linux Ubuntu 24.04 LTS 6.8.0-147.147
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1097.104
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1067.70
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1097.106
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1071.79
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1093.99
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1066.74

ubuntu advisories UBUNTU-CVE-2025-38563

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-rt SLE Micro 5.4, SLE Micro 5.3 5.14.21-150400.15.145.1
  • kernel-source-rt SLE Micro 5.4, SLE Micro 5.3 5.14.21-150400.15.145.1
  • kernel-64kb SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS, SLE High Performance Computing 15 SP4-ESPOS 5.14.21-150400.24.194.1
  • kernel-syms SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS +1 more 5.14.21-150400.24.194.1
  • kernel-source SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS +1 more 5.14.21-150400.24.194.1
  • kernel-default SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Micro 5.4 +5 more 5.14.21-150400.24.194.1
  • kernel-obs-build SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS +1 more 5.14.21-150400.24.194.1
  • kernel-default-base SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Micro 5.4 +3 more 5.14.21-150400.24.194.1.150400.24.98.3

suse advisories SUSE-SU-2026:1131-1SUSE-SU-2026:0617-1SUSE-SU-2026:0496-1SUSE-SU-2026:0495-1SUSE-SU-2026:0475-1SUSE-SU-2026:0474-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.6.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-kvmsmall openSUSE Leap 16.0 6.12.0-160000.6.1

opensuse advisories openSUSE-SU-2025:20081-1

  • kernel Azure Linux 3.0 6.6.104.2-1
  • kernel CBL-Mariner 2.0 5.15.200.1-1

azure linux advisories AZL-66494AZL-73800

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-38563 updated cvss 4.4

kernel: Linux kernel: Denial of Service in perf subsystem due to VMA split

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3 d ago

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

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