Linux Kernel up to 6.16.0 mmap reference count

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CTI Interest Score
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6.6$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.1.147/6.6.101/6.12.41/6.15.9/6.16.0. It has been declared as critical. This affects the function mmap. The manipulation results in reference count. This vulnerability is reported as CVE-2025-38563. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.1.147/6.6.101/6.12.41/6.15.9/6.16.0. Affected is the function mmap. The manipulation with an unknown input leads to a reference count vulnerability. CWE is classifying the issue as CWE-911. The product uses a reference count to manage a resource, but it does not update or incorrectly updates the reference count. This is going to have an impact on availability. CVE summarizes:

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.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2025-38563 since 04/16/2025. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 260131 (Linux Distros Unpatched Vulnerability : CVE-2025-38563), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.1.148, 6.6.102, 6.12.42, 6.15.10, 6.16.1 or 6.17-rc1 eliminates this vulnerability. Applying the patch 7b84cb58d1f0aa07656802eae24689566e5f5b1b/6757a31a8e295ae4f01717a954afda173f25a121/e529888b7e8092912dd8789bdfc76685ccd2ff5f/ff668930871e0198c7f4e325058b8b7c286787bd/65311aad4c808bedad0c05d9bb8b06c47dae73eb/b024d7b56c77191cde544f838debb7f8451cd0d6 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (260131), EUVD (EUVD-2025-26105) and CERT Bund (WID-SEC-2025-1931). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

  • Open Source Linux Kernel

Productinfo

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Version

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.7
VulDB Meta Temp Score: 6.6

VulDB Base Score: 5.7
VulDB Temp Score: 5.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.8
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Reference count
CWE: CWE-911 / CWE-664
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 260131
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2025-38563

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.1.148/6.6.102/6.12.42/6.15.10/6.16.1/6.17-rc1
Patch: 7b84cb58d1f0aa07656802eae24689566e5f5b1b/6757a31a8e295ae4f01717a954afda173f25a121/e529888b7e8092912dd8789bdfc76685ccd2ff5f/ff668930871e0198c7f4e325058b8b7c286787bd/65311aad4c808bedad0c05d9bb8b06c47dae73eb/b024d7b56c77191cde544f838debb7f8451cd0d6

Timelineinfo

04/16/2025 CVE reserved
08/19/2025 +125 days Advisory disclosed
08/19/2025 +0 days VulDB entry created
01/09/2026 +143 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-38563 (🔒)
GCVE (CVE): GCVE-0-2025-38563
GCVE (VulDB): GCVE-100-320592
EUVD: 🔒
CERT Bund: WID-SEC-2025-1931 - Linux Kernel: Schwachstelle ermöglicht Privilegieneskalation

Entryinfo

Created: 08/19/2025 19:24
Updated: 01/09/2026 05:49
Changes: 08/19/2025 19:24 (58), 09/01/2025 05:28 (7), 09/01/2025 08:59 (2), 10/10/2025 18:34 (1), 10/11/2025 01:13 (1), 01/09/2026 05:49 (11)
Complete: 🔍
Cache ID: 216::103

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