CVE-2026-53373
Received Received - Intake

Linux Kernel mmap_prepare VMA Unmap Issue

Publication date: 2026-07-19

Last updated on: 2026-07-19

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: mm/vma: do not try to unmap a VMA if mmap_prepare() invoked from mmap() The mmap_prepare hook functionality includes the ability to invoke mmap_prepare() from the mmap() hook of existing 'stacked' drivers, that is ones which are capable of calling the mmap hooks of other drivers/file systems (e.g. overlayfs, shm). As part of the mmap_prepare action functionality, we deal with errors by unmapping the VMA should one arise. This works in the usual mmap_prepare case, as we invoke this action at the last moment, when the VMA is established in the maple tree. However, the mmap() hook passes a not-fully-established VMA pointer to the caller (which is the motivation behind the mmap_prepare() work), which is detached. So attempting to unmap a VMA in this state will be problematic, with the most obvious symptom being a warning in vma_mark_detached(), because the VMA is already detached. It's also unncessary - the mmap() handler will clean up the VMA on error. So to fix this issue, this patch propagates whether or not an mmap action is being completed via the compatibility layer or directly. If the former, then we do not attempt VMA cleanup, if the latter, then we do. This patch also updates the userland VMA tests to reflect the change.

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Meta Information

Published
2026-07-19
Last Modified
2026-07-19
Generated
2026-07-20
AI Q&A
2026-07-19
EPSS Evaluated
N/A
NVD
CVE-2026-53373
EUVD
EUVD-2026-45446

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
linux linux_kernel *
linux_kernel linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves an issue where the mmap_prepare hook attempts to unmap a VMA (Virtual Memory Area) that is not fully established. This happens when mmap_prepare is called from stacked drivers like overlayfs or shm. The VMA is detached at this stage, leading to potential warnings or errors in vma_mark_detached(). The fix ensures that VMA cleanup is skipped when using the compatibility layer to avoid this problem.

Detection Guidance

This vulnerability is specific to the Linux kernel's memory management and does not have a direct network-based detection method. It may manifest as kernel warnings or errors related to VMA detachment during mmap operations. Check kernel logs for messages about vma_mark_detached() or mmap_prepare() failures using commands like dmesg or journalctl -k.

Impact Analysis

This vulnerability primarily affects the stability of the Linux kernel when using stacked drivers that call mmap hooks. It may cause system warnings or errors during memory mapping operations, potentially leading to crashes or unexpected behavior in affected systems.

Compliance Impact

This vulnerability is a Linux kernel issue related to memory management during VMA operations. It does not directly impact compliance with standards like GDPR or HIPAA, as those focus on data protection and privacy rather than kernel memory handling.

Mitigation Strategies

Update your Linux kernel to the latest stable version that includes the fix for CVE-2026-53373. This vulnerability is resolved in kernel versions incorporating the mmap_prepare() patch. Monitor kernel updates from your distribution vendor and apply them promptly.

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