CVE-2026-64596
Received Received - Intake

Linux Kernel SB_I_NOEXEC and SB_I_NODEV Flag Defaults

Publication date: 2026-08-06

Last updated on: 2026-08-06

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: libfs: set SB_I_NOEXEC and SB_I_NODEV by default in init_pseudo() Since commit 1e7ab6f67824 ("anon_inode: rework assertions"), path_noexec() warns when an anonymous-inode file is mmap'd from a superblock that has not set SB_I_NOEXEC. dma-buf backs its files this way and never set the flag, so mmap of any exported buffer trips the warning on a CONFIG_DEBUG_VFS=y kernel: WARNING: CPU: 11 PID: 121813 at fs/exec.c:118 path_noexec+0x47/0x50 do_mmap+0x2b5/0x680 vm_mmap_pgoff+0x129/0x210 ksys_mmap_pgoff+0x177/0x240 __x64_sys_mmap+0x33/0x70 init_pseudo() sets up internal SB_NOUSER mounts that are never path-reachable. Set both flags here so every pseudo filesystem gets them by default instead of each caller setting them. SB_I_NODEV is inert for unreachable mounts. SB_I_NOEXEC has one visible effect: an executable mapping of a pseudo-fs fd, such as a dma-buf, now fails with -EPERM, which is the invariant the assertion enforces. No in-tree caller maps these executable. Reproduce on CONFIG_DEBUG_VFS=y: make -C tools/testing/selftests/dmabuf-heaps sudo ./tools/testing/selftests/dmabuf-heaps/dmabuf-heap -t system

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-08-06
Last Modified
2026-08-06
Generated
2026-08-06
AI Q&A
2026-08-06
EPSS Evaluated
N/A
NVD
CVE-2026-64596
EUVD
EUVD-2026-53783

Affected Vendors & Products

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

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-UNKNOWN

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

This vulnerability in the Linux kernel involves a missing security flag in pseudo filesystems. The issue occurs because init_pseudo() does not set SB_I_NOEXEC and SB_I_NODEV flags by default, which are required to prevent execution and device access on certain filesystems. This can lead to warnings or errors when anonymous-inode files are mmap'd, particularly affecting dma-buf files used for memory sharing.

Detection Guidance

This vulnerability triggers a warning on kernels with CONFIG_DEBUG_VFS=y when an anonymous-inode file is mmap'd from a superblock without SB_I_NOEXEC. Check kernel logs for messages like 'WARNING: CPU: ... path_noexec+0x47' during dma-buf operations.

Impact Analysis

The impact is primarily on systems using CONFIG_DEBUG_VFS=y kernels. Users may see warnings when mapping dma-buf files, and executable mappings of pseudo-filesystem files may fail with -EPERM. However, no in-tree code currently maps these files executable, so real-world impact is likely minimal.

Mitigation Strategies

Apply the kernel patch that sets SB_I_NOEXEC and SB_I_NODEV by default in init_pseudo(). Update to a kernel version containing the fix or backport the commit 1e7ab6f67824.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-64596. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart