high CVSS 7.8 EPSS <0.1%

CVE-2024-49960·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: ext4: fix timer use-after-free on failed mount Syzbot has found an ODEBUG bug in ext4_fill_super The del_timer_sync function cancels the s_err_report timer, which reminds about filesystem errors daily. We should guarantee the timer is no longer active before kfree(sbi). When filesystem mounting fails, the flow goes to failed_mount3, where an error occurs when ext4_stop_mmpd is called, causing a read I/O failure. This triggers the ext4_handle_error function that ultimately re-arms the timer, leaving the s_err_report timer active before kfree(sbi) is called. Fix the issue by canceling the s_err_report timer after calling ext4_stop_mmpd.

Severity
high
Software
Kernel
Fixed in
6.11.3
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% — in the bottom 1% 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-2024-49960 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: 6.11

Until: 6.11.3

Fixed in: 6.11.3

How to fix this CVE

Update your Linux kernel to version 6.11.3 or later to fix a use-after-free vulnerability in ext4 mount error handling. This flaw occurs when filesystem mounting fails and leaves the error reporting timer active before memory deallocation, potentially causing kernel crashes. Apply the update immediately to systems running kernel versions 6.11 through 6.11.2.

sudo dnf update kernel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your kernel version with `uname -r` and verify if it falls in the 6.11.0–6.11.2 range
  2. Step 2: Confirm ext4 filesystem is in use by running `df -T | grep ext4` to identify vulnerable mount points
  3. Step 3: Search kernel logs for ext4 mount failures with `dmesg | grep -i 'ext4.*failed\|ext4.*error'` to detect past exploitation attempts
  4. Step 4: After patching to 6.11.3+, verify the update with `uname -r` and reboot to ensure the new kernel is active

FAQ

What is CVE-2024-49960?

This is a use-after-free memory bug in Linux kernel ext4 filesystem handling where a timer object remains active after its memory is freed during failed mount operations, causing potential kernel crashes or memory corruption.

Is CVE-2024-49960 being actively exploited?

No, CVE-2024-49960 is not listed in CISA's known exploited vulnerabilities catalog and no public exploits are currently available, though the vulnerability has high severity.

What versions of Kernel are affected by CVE-2024-49960?

Linux kernel versions 6.11.0 through 6.11.2 are vulnerable. Version 6.11.3 and later contain the fix.

How do I check if my server is vulnerable to CVE-2024-49960?

Run `uname -r` and compare the output to 6.11.0–6.11.2; if your kernel version is in this range, your system is vulnerable. Cross-reference with `cat /etc/os-release` to confirm your distribution.

Does Defensia detect CVE-2024-49960?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2024-49960 will appear in your dashboard with remediation steps.

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References

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