⚠ Reference material — not professional advice. Test in staging, back up first, verify against your specific version. Use your own judgment for your environment.
● High · CVSS 7.1

How to Fix CVE-2026-31766: drm/amdgpu: validate doorbell_offset in Linux

By Sai Kiran Pandrala

Other vulnerabilities in the same area that are worth patching alongside this one:

Last verified: 2026-05-25

CVE-2026-31766 is a drm/amdgpu: validate doorbell_offset in Linux Linux. Fix it by upgrading to 6.18.22, 6.19.12, 7.0.

⚡ At a glance
SeverityCVSS 7.1 - High
Actively exploited?Not currently in the CISA KEV catalog
AffectedLinux f09c1e6077abd1bc2ddd2b97e1135215801ca7f9 up to (excluding) 3543005a42d7e8e12b21897ef6798541bf7cbcd3; Linux f09c1e6077abd1bc2ddd2b97e1135215801ca7f9 up to (excluding) 86b732fbc37ce4fb76cdd4af0fb7e30a6acdbce6; Linux f09c1e6077abd1bc2ddd2b97e1135215801ca7f9 up to (excluding) a018d1819f158991b7308e4f74609c6c029b670c; Linux 6.16
Fixed in6.18.22, 6.19.12, 7.0
Type (CWE)Not verified

What is CVE-2026-31766?

CVE-2026-31766 is a drm/amdgpu: validate doorbell_offset flaw in Linux Linux. It carries a CVSS base score of 7.1 (high). It is not currently listed in the CISA Known Exploited Vulnerabilities catalog.

From the source record: In the Linux kernel, the following vulnerability has been resolved:

drm/amdgpu: validate doorbell_offset in user queue creation

amdgpu_userq_get_doorbell_index() passes the user-provided

doorbell_offset to amdgpu_doorbell_index_on_bar() without bounds

checking. An arbitrarily large doorbell_offset can cause the

calculated doorbell index to fall outside the allocated doorbell BO,

potentially corrupting kernel doorbell space.

Validate that doorbell_offset falls within the doorbell BO before

computing the BAR index, using u64 arithmetic to prevent overflow.

(cherry picked from commit de1ef4ffd70e1d15f0bf584fd22b1f28cbd5e2ec)

Why it matters in practice: The blast radius depends on how the affected service is exposed. An internet-facing instance with no compensating controls is the highest-risk configuration.

Am I affected?

You are affected if your installation of Linux matches a version listed in the Affected row above.


# Debian/Ubuntu
dpkg -s linux | grep Version
# RHEL/Rocky
rpm -q linux

How to fix CVE-2026-31766

Apply the vendor patch. Target the build named in the Fixed in row above (6.18.22, 6.19.12, 7.0). The runnable command set below covers the most common deployment patterns for Linux.

Ubuntu / Debian


sudo apt-get update
sudo apt-get install --only-upgrade linux
dpkg -s linux | grep Version

RHEL / CentOS / Rocky


sudo dnf upgrade linux -y
rpm -q linux

After applying the patch

  1. Restart the service or device so the patched binary loads.
  2. Confirm the running version matches the Fixed in row using the verification command below.
  3. Rotate credentials and API keys that the affected service could access if the asset was exposed during the disclosure window.

If you can't patch immediately

Until the patch lands, narrow the attack surface with these runnable controls.

Restrict network exposure

Block public access to the affected service at the perimeter. Allow only trusted source IPs.


# Linux iptables: only allow trusted admin subnet
sudo iptables -A INPUT -p tcp --dport 443 -s 10.10.10.0/24 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 443 -j DROP
sudo iptables-save | sudo tee /etc/iptables/rules.v4


# Windows firewall: only allow trusted admin subnet on management port
New-NetFirewallRule -DisplayName "Restrict-Mgmt-Allow" -Direction Inbound -Action Allow `
  -RemoteAddress 10.10.10.0/24 -Protocol TCP -LocalPort 443
New-NetFirewallRule -DisplayName "Restrict-Mgmt-Deny"  -Direction Inbound -Action Block `
  -Protocol TCP -LocalPort 443

Mitigations are temporary. Apply the vendor patch as soon as a maintenance window opens.

How to verify the fix worked

Confirm the patched build is the one actually running.


# Debian/Ubuntu
dpkg -s linux | grep Version
# RHEL/Rocky
rpm -q linux

Expected: a version at or above 6.18.22, 6.19.12, 7.0.

Also worth doing: pull recent log windows for indicators of compromise listed in the vendor advisory, and re-run an authenticated vulnerability scan with up-to-date signatures.

Frequently asked questions

Is CVE-2026-31766 being exploited in the wild?

As of 2026-05-25, CVE-2026-31766 is not listed in the CISA Known Exploited Vulnerabilities catalog. Watch the catalog and patch on a normal cadence; KEV status can change as exploitation evidence emerges.

What is the CVSS score for CVE-2026-31766?

The CVSS base score is 7.1 (High).

What version fixes this?

Upgrade to 6.18.22, 6.19.12, 7.0.

Will a WAF or IDS rule alone close this?

No. Network filters cut down opportunistic scans but they do not remove the flaw. The vendor patch is the only durable fix.

References

*Assembled from the official vendor advisory, the NVD record, and the CISA KEV listing on 2026-05-25. Always confirm against the vendor advisory before applying changes in production.*