high CVSS 7.8 EPSS <0.1%

CVE-2024-53143·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: fsnotify: Fix ordering of iput() and watched_objects decrement Ensure the superblock is kept alive until we're done with iput(). Holding a reference to an inode is not allowed unless we ensure the superblock stays alive, which fsnotify does by keeping the watched_objects count elevated, so iput() must happen before the watched_objects decrement. This can lead to a UAF of something like sb->s_fs_info in tmpfs, but the UAF is hard to hit because race orderings that oops are more likely, thanks to the CHECK_DATA_CORRUPTION() block in generic_shutdown_super(). Also, ensure that fsnotify_put_sb_watched_objects() doesn't call fsnotify_sb_watched_objects() on a superblock that may have already been freed, which would cause a UAF read of sb->s_fsnotify_info.

Severity
high
Software
Kernel
Fixed in
6.12.2
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at <0.1% — higher than 14% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2024-53143 scores 7.8 on CVSS, so a successful attack would be serious — but at <0.1%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

From: 6.12

Until: 6.12.2

Fixed in: 6.12.2

How to fix this CVE

Update your Linux kernel to version 6.12.2 or later to resolve a use-after-free vulnerability in the fsnotify subsystem that could corrupt memory or crash the system. Systems running kernel versions 6.12.0 through 6.12.1 should prioritize this update, as the vulnerability affects reference counting logic during inode cleanup operations.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check installed kernel version with `uname -r` and verify if it falls within 6.12.0-6.12.1
  2. Step 2: Confirm fsnotify is active by checking `cat /proc/sys/fs/inotify/max_user_watches` (non-zero indicates fsnotify usage)
  3. Step 3: Search system logs for UAF-related crashes with `dmesg | grep -i 'use-after-free\|KASAN\|page fault' | tail -20`
  4. Step 4: After patching, verify new kernel is loaded with `uname -r` and confirm it shows version 6.12.2 or later, then reboot if necessary

FAQ

What is CVE-2024-53143?

A use-after-free vulnerability in Linux kernel's fsnotify (file system notification) subsystem where the superblock reference count is decremented before the inode is properly released, potentially allowing memory corruption or kernel crashes in systems using file monitoring features.

Is CVE-2024-53143 being actively exploited?

No, this vulnerability is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog and no public exploits are currently available, though the vulnerability was discovered through Google Project Zero research.

What versions of Kernel are affected by CVE-2024-53143?

Linux kernel versions 6.12.0, 6.12.1, and 6.12.2 (pre-patch) are affected; version 6.12.2 and later include the fix.

How do I check if my server is vulnerable to CVE-2024-53143?

Run `uname -r` to display your kernel version; if it shows 6.12.0 or 6.12.1, your system is vulnerable and requires immediate kernel update.

Does Defensia detect CVE-2024-53143?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2024-53143 will appear in your dashboard with remediation steps.

Related Kernel CVEs

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References

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