high CVSS 7.8 EPSS <0.1%

CVE-2021-47148·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: octeontx2-pf: fix a buffer overflow in otx2_set_rxfh_context() This function is called from ethtool_set_rxfh() and "*rss_context" comes from the user. Add some bounds checking to prevent memory corruption.

Severity
high
Software
Kernel
Fixed in
5.12.9
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% — 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.

Read the two together. CVE-2021-47148 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: 5.12

Until: 5.12.9

Fixed in: 5.12.9

How to fix this CVE

Update your Linux kernel to version 5.12.9 or later to patch a buffer overflow vulnerability in the OcteonTX2 packet filtering driver's RSS context handler. This vulnerability allows local users with standard privileges to corrupt kernel memory through improper bounds checking in the ethtool RSS configuration interface. Immediate patching is recommended for systems running affected kernel versions, particularly those using OcteonTX2 network adapters.

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` and verify it is 5.12.9 or later
  2. Step 2: Confirm OcteonTX2 driver presence by running `lspci | grep -i octeon` or check `/sys/class/net/*/device/driver` for otx2 references
  3. Step 3: Review kernel logs for memory corruption indicators with `dmesg | grep -i 'BUG\|Oops\|segfault'` around the time frame of suspicious ethtool activity
  4. Step 4: Verify the patch application by comparing kernel configuration: `grep CONFIG_OCTEONTX2_PF /boot/config-$(uname -r)` should show the driver is compiled, then confirm version via `uname -r` shows 5.12.9+

FAQ

What is CVE-2021-47148?

This vulnerability is a buffer overflow in the OcteonTX2 packet filter driver's RSS context configuration function. It allows local users to trigger kernel memory corruption by providing malformed RSS context parameters through ethtool, potentially leading to privilege escalation or system crash.

Is CVE-2021-47148 being actively exploited?

No, this vulnerability is not currently listed in CISA's Known Exploited Vulnerabilities catalog and no public exploits are available. However, the high CVSS score (7.8) and local privilege escalation potential make it a high-priority patch.

What versions of Kernel are affected by CVE-2021-47148?

Linux kernel versions 5.12 through 5.12.8 are vulnerable. The vulnerability was fixed in kernel version 5.12.9.

How do I check if my server is vulnerable to CVE-2021-47148?

Run `uname -r` to check your kernel version. If it shows 5.12.0 through 5.12.8, your system is vulnerable. Additionally, verify OcteonTX2 driver is active with `lsmod | grep otx2`.

Does Defensia detect CVE-2021-47148?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2021-47148 will appear in your dashboard with remediation steps.

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References

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