medium CVSS 5.5 EPSS <0.1%

CVE-2021-47351·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: ubifs: Fix races between xattr_{set|get} and listxattr operations UBIFS may occur some problems with concurrent xattr_{set|get} and listxattr operations, such as assertion failure, memory corruption, stale xattr value[1]. Fix it by importing a new rw-lock in @ubifs_inode to serilize write operations on xattr, concurrent read operations are still effective, just like ext4. [1] https://lore.kernel.org/linux-mtd/20200630130438.141649-1-houtao1@huawei.com

Severity
medium
Software
Kernel
Fixed in
5.13.3
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% — higher than 6% 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.

Affected versions

From: 5.13

Until: 5.13.3

Fixed in: 5.13.3

How to fix this CVE

Update the Linux kernel to version 5.13.3 or later to resolve race conditions in UBIFS extended attribute operations. This fix serializes concurrent xattr_{set|get} and listxattr operations to prevent memory corruption, assertion failures, and stale attribute values. Reboot your system after applying the kernel update to ensure the patched version is active.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your installed kernel version with `uname -r` and verify if it falls within the vulnerable range (5.13.0 to 5.13.3)
  2. Step 2: Determine UBIFS usage by running `mount | grep ubifs` to check if any filesystems are mounted with UBIFS
  3. Step 3: Search kernel logs for xattr-related errors using `dmesg | grep -i 'ubifs\|xattr\|assertion'` or check journal logs with `journalctl -k | grep -i 'ubifs\|xattr'`
  4. Step 4: After patching, verify the new kernel is running with `uname -r` and confirm it shows version 5.13.3 or later, then validate UBIFS mount stability with `mount | grep ubifs`

FAQ

What is CVE-2021-47351?

This vulnerability affects UBIFS (UBI filesystem) in the Linux kernel where concurrent read and write operations on extended attributes could trigger race conditions, leading to assertion failures, memory corruption, or retrieval of stale attribute values.

Is CVE-2021-47351 being actively exploited?

No, there is no evidence of active exploitation or publicly available exploits for this vulnerability. It is a local kernel race condition that requires filesystem-level interaction.

What versions of Kernel are affected by CVE-2021-47351?

Linux kernel versions 5.13.0 through 5.13.3 are vulnerable. The fix was included in kernel version 5.13.3 and later.

How do I check if my server is vulnerable to CVE-2021-47351?

Run `uname -r` to check your kernel version. If it returns a version between 5.13.0 and 5.13.2, your system is vulnerable. Additionally, run `mount | grep ubifs` to confirm UBIFS usage.

Does Defensia detect CVE-2021-47351?

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-2021-47351 will appear in your dashboard with remediation steps.

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References

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