high CVSS 7.8 EPSS <0.1%

CVE-2021-47489·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu: Fix even more out of bound writes from debugfs CVE-2021-42327 was fixed by: commit f23750b5b3d98653b31d4469592935ef6364ad67 Author: Thelford Williams <tdwilliamsiv@gmail.com> Date: Wed Oct 13 16:04:13 2021 -0400 drm/amdgpu: fix out of bounds write but amdgpu_dm_debugfs.c contains more of the same issue so fix the remaining ones. v2: * Add missing fix in dp_max_bpc_write (Harry Wentland)

Severity
high
Software
Kernel
Fixed in
5.14.16
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-2021-47489 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: 5.11

Until: 5.14.16

Fixed in: 5.14.16

How to fix this CVE

Update your Linux kernel to version 5.14.16 or later to patch out-of-bounds write vulnerabilities in the AMD GPU debugfs interface. This vulnerability allows local users with privileged access to write beyond allocated buffer boundaries through debugfs operations. Apply the kernel update and reboot your system to remediate the issue.

sudo dnf update kernel kernel-devel && sudo reboot

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your current kernel version with `uname -r` and compare against the affected range 5.11 to 5.14.15
  2. Step 2: Verify AMD GPU driver presence with `lspci | grep -i amd` and check if debugfs is mounted via `mount | grep debugfs`
  3. Step 3: Search system logs for debugfs write attempts with `grep -r 'amdgpu.*debugfs' /var/log/` to identify suspicious activity patterns
  4. Step 4: After patching, confirm kernel version is 5.14.16 or later using `uname -r` and verify no regression with `dmesg | tail -20`

FAQ

What is CVE-2021-47489?

CVE-2021-47489 is a local privilege escalation vulnerability in the Linux kernel's AMD GPU (amdgpu) debugfs implementation that allows out-of-bounds memory writes. An authenticated local attacker can exploit this through the debugfs interface to corrupt kernel memory and achieve elevated privileges.

Is CVE-2021-47489 being actively exploited?

No, CVE-2021-47489 is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog and no public exploits are currently available. However, the vulnerability is locally exploitable and should be patched promptly.

What versions of Kernel are affected by CVE-2021-47489?

Linux kernel versions 5.11 through 5.14.15 are affected. Kernel 5.14.16 and all subsequent releases contain the fix.

How do I check if my server is vulnerable to CVE-2021-47489?

Run `uname -r` to get your kernel version. If it returns a version between 5.11 and 5.14.15 inclusive, your system is vulnerable. Verify AMD GPU presence with `lspci | grep -i amd`.

Does Defensia detect CVE-2021-47489?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server running versions 5.11-5.14.15, CVE-2021-47489 will appear in your dashboard with remediation steps.

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References

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