CVE-2026-64074
Received Received - Intake

fs/statmount slab out-of-bounds write in Linux kernel

Vulnerability report for CVE-2026-64074, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

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: fs/statmount: fix slab out-of-bounds write in statmount_mnt_idmap statmount_mnt_idmap() writes one mapping with seq_printf() and then manually advances seq->count to include the NUL separator. If seq_printf() overflows, seq_set_overflow() sets seq->count to seq->size. The manual seq->count++ changes this to seq->size + 1. seq_has_overflowed() then no longer detects the overflow. The corrupted count returns to statmount_string(), which later executes: seq->buf[seq->count++] = '\0'; This causes a 1-byte NULL out-of-bounds write on the dynamically allocated seq buffer. Fix this by checking for overflow immediately after seq_printf().

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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
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

Helpful Resources

Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a Linux kernel vulnerability where a function called statmount_mnt_idmap() incorrectly handles buffer overflow in a sequence output function. It writes data and manually adjusts the buffer count, which can mask an overflow condition. This leads to a one-byte out-of-bounds write when a null terminator is added to the corrupted buffer.

Detection Guidance

This vulnerability is specific to the Linux kernel's fs/statmount component and requires kernel-level access to detect. There are no direct network-based detection methods. You can check your kernel version against patched versions or monitor for crashes in statmount-related operations.

Impact Analysis

This vulnerability could allow an attacker with local access to cause memory corruption in the kernel, potentially leading to system crashes, privilege escalation, or other unexpected behavior. It may also enable denial-of-service conditions on affected systems.

Compliance Impact

This vulnerability is a low-level kernel memory corruption issue that could lead to system instability or crashes. It does not directly affect data confidentiality, integrity, or access controls typically governed by GDPR or HIPAA. Compliance impact would be indirect if the vulnerability enables denial-of-service conditions affecting systems processing regulated data.

Mitigation Strategies

Apply the latest kernel security updates from your Linux distribution. If no patch is available, consider disabling or restricting access to mount-related operations until patched. Monitor kernel logs for crashes or errors in statmount functionality.

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