---
id: CVE-2026-64074
title: |-
  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 i…
summary: |-
  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 i…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-787
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 6.15, < 6.18.34'
  - 'linux_kernel >= 6.19, < 7.0.11'
  - linux_kernel = 7.1
patched:
  - linux_kernel 7.0.11
published: '2026-07-19'
updated: '2026-09-03'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64074'
references:
  - url: 'https://git.kernel.org/stable/c/93614949dc86f068e3c32c32cf1ee2a2323177a7'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a3bf0f28d4ba16e1f35f8c983bb04426b87e2a78'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e37ea2c6f17f273813ea4e8e94c102591d598ce1'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00127
epssPercentile: 0.02734
ingestedAt: '2026-09-04T05:15:22.705Z'
---

## Overview

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().

## Affected

- `linux_kernel >= 6.15, < 6.18.34`
- `linux_kernel >= 6.19, < 7.0.11`
- `linux_kernel = 7.1`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.0.11`