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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 28 Jul 2023.
Bifrost Gpu Kernel DriverApplication · Arm

CVE-2021-29256

HIGH · 8.8 CVSS v3.1 Published 2021-05-24
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 an unprivileged user to achieve access to freed memory, leading to information disclosure or root privilege escalation. This affects Bifrost r16p0 through r29p0 before r30p0, Valhall r19p0 through r29p0 before r30p0, and Midgard r28p0 through r30p0.

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

Use-after-free vulnerability in Arm Mali GPU kernel driver allows unprivileged users to access freed memory, potentially leading to information disclosure or privilege escalation to root. Affects Bifrost (r16p0-r29p0), Valhall (r19p0-r29p0), and Midgard (r28p0-r30p0) versions before r30p0.

MitigationUpdate Mali GPU kernel driver to r30p0 or later version. Prioritize systems with untrusted users or network-facing GPU workloads given the high CVSS and privilege escalation potential.

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:>= r16p0, < r30p0
Midgard Gpu Kernel DriverApplication
Affected:>= r28p0, < r31p0
Valhall Gpu Kernel DriverApplication
Affected:>= r19p0, < r30p0

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 hardware
    Check system hardware info (lspci, /proc/bus/pci, or device tree) for Mali GPU presence
    Affected if System has an Arm Mali GPU (Bifrost, Valhall, or Midgard architecture)
  2. Locate Mali kernel driver module
    Query loaded kernel modules (lsmod) or check /sys/module/ for mali, mali_kbase, or similar Mali GPU driver modules
    Affected if A Mali GPU kernel driver module is loaded in memory
  3. Retrieve driver version
    Use modinfo on the driver module or read version from /sys/module/<modulename>/version to obtain the rXpY version string
    Affected if Version string matches the pattern rXpY where X and Y are version numbers
  4. Compare against affected Bifrost versions
    If using Bifrost driver, compare retrieved version: affected if r16p0 <= version < r30p0
    Affected if Bifrost version is r16p0 or higher but below r30p0
  5. Compare against affected Valhall versions
    If using Valhall driver, compare retrieved version: affected if r19p0 <= version < r30p0
    Affected if Valhall version is r19p0 or higher but below r30p0
  6. Compare against affected Midgard versions
    If using Midgard driver, compare retrieved version: affected if r28p0 <= version < r31p0
    Affected if Midgard version is r28p0 or higher but below r31p0

User is affected if the system has an Arm Mali GPU with a kernel driver version in the vulnerable range for their architecture (Bifrost r16p0-r29p0, Valhall r19p0-r29p0, or Midgard r28p0-r30p0).

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

Update Mali GPU kernel driver to r30p0 or later version. Prioritize systems with untrusted users or network-facing GPU workloads given the high CVSS and privilege escalation potential.

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 variant in use (Bifrost, Midgard, or Valhall) by checking the driver version through system logs or /sys/class/misc/mali0/device/version
  2. 2. For Bifrost: upgrade to driver version r30p0 or later
  3. 3. For Valhall: upgrade to driver version r30p0 or later
  4. 4. For Midgard: upgrade to driver version r31p0 or later
  5. 5. Obtain the updated GPU kernel driver from the Arm developer portal (developer.arm.com) or through the device/OS vendor's security update channel
  6. 6. Apply the driver update following the vendor's standard update procedure for GPU kernel modules
  7. 7. Reboot the system to load the patched driver
  8. 8. Verify the driver version has been updated and matches the fixed release
Caveat Driver updates may require kernel version compatibility checks; ensure the target kernel version supports the new GPU driver

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
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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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-2021-29256 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data