medium CVSS 5.5 EPSS <0.1%

CVE-2021-47374·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: dma-debug: prevent an error message from causing runtime problems For some drivers, that use the DMA API. This error message can be reached several millions of times per second, causing spam to the kernel's printk buffer and bringing the CPU usage up to 100% (so, it should be rate limited). However, since there is at least one driver that is in the mainline and suffers from the error condition, it is more useful to err_printk() here instead of just rate limiting the error message (in hopes that it will make it easier for other drivers that suffer from this issue to be spotted).

Severity
medium
Software
Kernel
Fixed in
5.14.9
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.

Affected versions

Until: 5.14.9

Fixed in: 5.14.9

How to fix this CVE

Update your Linux kernel to version 5.14.9 or later to resolve a DMA debugging issue that can cause excessive kernel log spam and CPU exhaustion under certain driver conditions. This vulnerability affects systems running kernels prior to 5.14.9 that use DMA API with drivers that trigger the vulnerable code path repeatedly.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your current kernel version with: uname -r
  2. Step 2: Compare the version output to 5.14.9—if your version is lower, you are vulnerable
  3. Step 3: Search kernel logs for repeated 'dma-debug' error messages with: grep -c 'dma-debug' /var/log/kern.log
  4. Step 4: After applying the patch, reboot and verify the new kernel is active with: uname -r

FAQ

What is CVE-2021-47374?

CVE-2021-47374 is a denial-of-service vulnerability in the Linux kernel's DMA debugging subsystem. Certain drivers using the DMA API can trigger an error condition repeatedly, flooding the kernel log buffer and consuming CPU resources without rate limiting.

Is CVE-2021-47374 being actively exploited?

No, CVE-2021-47374 is not actively exploited in the wild according to CISA KEV data, and no public exploits are available. Exploitation requires specific hardware and driver configurations.

What versions of Kernel are affected by CVE-2021-47374?

All Linux kernel versions prior to 5.14.9 are affected. The vulnerability was fixed in kernel 5.14.9 and later stable releases.

How do I check if my server is vulnerable to CVE-2021-47374?

Run 'uname -r' to display your kernel version. If it is lower than 5.14.9, your system is vulnerable to this DMA debugging issue.

Does Defensia detect CVE-2021-47374?

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-2021-47374 will appear in your dashboard with remediation steps.

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References

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