high CVSS 7.8

CVE-2024-36963·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: tracefs: Reset permissions on remount if permissions are options There's an inconsistency with the way permissions are handled in tracefs. Because the permissions are generated when accessed, they default to the root inode's permission if they were never set by the user. If the user sets the permissions, then a flag is set and the permissions are saved via the inode (for tracefs files) or an internal attribute field (for eventfs). But if a remount happens that specify the permissions, all the files that were not changed by the user gets updated, but the ones that were are not. If the user were to remount the file system with a given permission, then all files and directories within that file system should be updated. This can cause security issues if a file's permission was updated but the admin forgot about it. They could incorrectly think that remounting with permissions set would update all files, but miss some. For example: # cd /sys/kernel/tracing # chgrp 1002 current_tracer # ls -l [..] -rw-r----- 1 root root 0 May 1 21:25 buffer_size_kb -rw-r----- 1 root root 0 May 1 21:25 buffer_subbuf_size_kb -r--r----- 1 root root 0 May 1 21:25 buffer_total_size_kb -rw-r----- 1 root lkp 0 May 1 21:25 current_tracer -rw-r----- 1 root root 0 May 1 21:25 dynamic_events -r--r----- 1 root root 0 May 1 21:25 dyn_ftrace_total_info -r--r----- 1 root root 0 May 1 21:25 enabled_functions Where current_tracer now has group "lkp". # mount -o remount,gid=1001 . # ls -l -rw-r----- 1 root tracing 0 May 1 21:25 buffer_size_kb -rw-r----- 1 root tracing 0 May 1 21:25 buffer_subbuf_size_kb -r--r----- 1 root tracing 0 May 1 21:25 buffer_total_size_kb -rw-r----- 1 root lkp 0 May 1 21:25 current_tracer -rw-r----- 1 root tracing 0 May 1 21:25 dynamic_events -r--r----- 1 root tracing 0 May 1 21:25 dyn_ftrace_total_info -r--r----- 1 root tracing 0 May 1 21:25 enabled_functions Everything changed but the "current_tracer". Add a new link list that keeps track of all the tracefs_inodes which has the permission flags that tell if the file/dir should use the root inode's permission or not. Then on remount, clear all the flags so that the default behavior of using the root inode's permission is done for all files and directories.

Severity: high
Software: Kernel
Fixed in: 6.8.10
Published: 2024-06-03

Affected versions

From: 6.7.4

Until: 6.8.10

Fixed in: 6.8.10

How to fix this CVE

Update your Linux kernel to version 6.8.10 or later to resolve a permission handling inconsistency in tracefs that could allow unprivileged users to retain elevated file permissions across filesystem remounts. This vulnerability affects kernel versions 6.7.4 through 6.8.10 and should be prioritized for systems managing sensitive tracing infrastructure.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

Check your kernel version: uname -r — compare against affected range 6.7.4 to 6.8.10
Verify tracefs is mounted: mount | grep tracefs — confirm /sys/kernel/tracing is present
List tracefs inode permissions: ls -l /sys/kernel/tracing/ | grep -v '^total' — identify files with non-default group ownership
After kernel update, verify fix: uname -r and confirm version is 6.8.10 or later, then remount tracefs with mount -o remount,gid=desired_group /sys/kernel/tracing and re-check permissions to ensure all files updated uniformly

FAQ

What is CVE-2024-36963?

This vulnerability allows tracefs files that have been individually permission-modified by users to retain their old permissions when the filesystem is remounted with new global permission settings, causing a mismatch where some files don't inherit the new remount-specified permissions as expected.

Is CVE-2024-36963 being actively exploited?

No, this vulnerability is not listed on the CISA KEV catalog and has no known public exploits or active exploitation in the wild.

What versions of Kernel are affected by CVE-2024-36963?

Linux kernel versions 6.7.4 through 6.8.9 are affected; the vulnerability is fixed in kernel 6.8.10 and later.

How do I check if my server is vulnerable to CVE-2024-36963?

Run uname -r and compare the output against the affected range (6.7.4–6.8.9); if your version falls within this range and tracefs is mounted, your system is vulnerable.

Does Defensia detect CVE-2024-36963?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2024-36963 will appear in your dashboard with remediation steps.

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References

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