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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 17 Nov 2021.
Bifrost Gpu Kernel DriverApplication · Arm

CVE-2021-28664

HIGH · 8.8 CVSS v3.1 Published 2021-05-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
In the wild Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The Arm Mali GPU kernel driver allows privilege escalation or a denial of service (memory corruption) because an unprivileged user can achieve read/write access to read-only pages. This affects Bifrost r0p0 through r29p0 before r30p0, Valhall r19p0 through r29p0 before r30p0, and Midgard r8p0 through r30p0 before r31p0.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The Arm Mali GPU kernel driver contains a vulnerability where unprivileged users can achieve read/write access to read-only memory pages. This allows local privilege escalation to higher privileges or can cause denial of service through memory corruption. The vulnerability affects Bifrost r0p0-r29p0, Valhall r19p0-r29p0, and Midgard r8p0-r30p0 GPU architectures.

MitigationApply the vendor-provided driver update: Bifrost and Valhall users should update to r30p0 or later, and Midgard users should update to r31p0 or later. Since this is a kernel-level driver vulnerability affecting multiple GPU generations, coordinate with your SoC/device manufacturer for the appropriate firmware/driver patch.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Bifrost Gpu Kernel DriverApplication
Affected:>= r0p0, < r29p0
Midgard Gpu Kernel DriverApplication
Affected:>= r8p0, < r31p0
Valhall Gpu Kernel DriverApplication
Affected:>= r19p0, < r29p0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Arm Mali GPU in system
    On Linux, run 'lspci | grep -i mali' or check if the mali kernel module is loaded with 'lsmod | grep mali'. On Android, check /proc/mali or /sys/class/misc/ for mali device entries.
    Affected if No Mali GPU or driver is present, so the system is not affected.
  2. Determine Mali driver version
    Run 'modinfo mali' to inspect the kernel module version, or check '/sys/module/mali/version' if available. On Android, try 'cat /sys/class/misc/mali0/device/gpu_version'.
    Affected if Unable to determine the driver version, so further verification is needed.
  3. Identify GPU architecture variant
    Examine the driver module name or version string. Bifrost drivers typically include 'bifrost' in the module filename, Midgard includes 'midgard', and Valhall includes 'valhall' in /sys/module/ or /lib/modules/.
    Affected if Cannot identify whether it is Bifrost, Midgard, or Valhall architecture.
  4. Compare version against vulnerable ranges
    Check the driver version number against these ranges: Bifrost (r0p0 to r28p0 inclusive are vulnerable, fixed in r29p0), Midgard (r8p0 to r30p0 inclusive are vulnerable, fixed in r31p0), Valhall (r19p0 to r28p0 inclusive are vulnerable, fixed in r29p0).
    Affected if The installed version falls within the affected range for the detected architecture: Bifrost < r29p0, Midgard < r31p0, or Valhall < r29p0.

The system is affected only if it runs an Arm Mali GPU with the Bifrost, Midgard, or Valhall kernel driver version that falls within the vulnerable ranges (Bifrost/Valhall < r29p0, Midgard < r31p0).

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor-provided driver update: Bifrost and Valhall users should update to r30p0 or later, and Midgard users should update to r31p0 or later. Since this is a kernel-level driver vulnerability affecting multiple GPU generations, coordinate with your SoC/device manufacturer for the appropriate firmware/driver patch.

Recommended fix High confidence

Bifrost: r30p0 or later; Valhall: r30p0 or later; Midgard: r31p0 or later

  1. 1. Identify the specific Arm Mali GPU kernel driver (Bifrost, Midgard, or Valhall) in use by checking the kernel module or system documentation.
  2. 2. For Bifrost GPU kernel driver: upgrade to r30p0 or later from the Arm Mali GPU kernel driver releases.
  3. 3. For Valhall GPU kernel driver: upgrade to r30p0 or later from the Arm Mali GPU kernel driver releases.
  4. 4. For Midgard GPU kernel driver: upgrade to r31p0 or later from the Arm Mali GPU kernel driver releases.
  5. 5. Verify the upgrade by checking the driver version matches or exceeds the fixed release (e.g., using 'cat /sys/class/misc/mali0/device/driver/version' or checking kernel logs).
  6. 6. Reboot the system or reload the kernel module to ensure the patched driver is loaded.
  7. 7. Test the GPU functionality to confirm normal operation after the update.
Caveat Major version upgrades to GPU drivers may introduce compatibility changes with user-space applications or require kernel version updates; test in non-production environment first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Bifrost Gpu Kernel Driver Exploited in the wild — priority engagement
  • Consultation8.0 h
  • Implementation4.0 h
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,840
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-28664 in production — separate from our analysis above.

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  • Version or environment caveats, and links to real fixes
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