CVE-2021-28663
Arm Mali Graphics Processing Unit (GPU) Use-After-Free Vulnerability
Description
CVE-2021-28663 is a HIGH vulnerability affecting Arm Mali Graphics Processing Unit (GPU), carrying a CVSS 3.1 score of 8.8. Arm Mali Graphics Processing Unit (GPU) kernel driver contains a use-after-free vulnerability that may allow a non-privileged user to make improper operations on GPU memory to gain root privilege, and/or disclose information. Affected products include arm bifrost gpu kernel driver (>= r0p0, < r29p0), arm midgard gpu kernel driver (>= r4p0, < r31p0), arm valhall gpu kernel driver (>= r19p0, < r29p0). This CVE is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog with a remediation deadline of 2021-11-17. With an EPSS score of 0.02417 (84.91th percentile), this vulnerability demonstrates significant real-world exploitation activity and should be prioritized for immediate remediation.
KEV Information
CVSS Score
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| arm | bifrost gpu kernel driver | >= r0p0, < r29p0 |
| arm | midgard gpu kernel driver | >= r4p0, < r31p0 |
| arm | valhall gpu kernel driver | >= r19p0, < r29p0 |
Multiple CVSS Assessments
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
- https://developer.arm.com/support/arm-security-updates(Vendor Advisory)
- https://developer.arm.com/support/arm-security-updates/mali-gpu-kernel-driver(Vendor Advisory)
- https://github.com/lntrx/CVE-2021-28663(Exploit)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-28663(US Government Resource)
Weakness Type
CWE-416: Use After Free
CVE-2021-28663 is classified under CWE-416 — Use After Free. This weakness category describes flaws where software continues to reference a memory location after it has been freed. When freed memory is reallocated, the dangling pointer can be exploited to corrupt data, disclose information, or execute arbitrary code. Use-after-free vulnerabilities are particularly dangerous in complex applications with manual memory management.
In the context of Arm Mali Graphics Processing Unit (GPU), this weakness is particularly concerning because use-after-free vulnerabilities in GPU kernel drivers can be leveraged to escalate privileges from user space to kernel level. Attackers can manipulate GPU memory operations to gain root access, potentially compromising the entire system. The combination of kernel-level access and GPU memory management complexity makes these flaws particularly difficult to detect and mitigate without vendor patches.
Learn more: CWE-416 — Use After Free
Impact Analysis
CVE-2021-28663 carries a CVSS 3.1 score of 8.8 (HIGH) with Unchanged Scope.
Confidentiality (HIGH): Successful exploitation grants the attacker extensive access to sensitive data processed by the affected system, including configuration files, credentials, and potentially data from connected systems.
Integrity (HIGH): Attackers can modify critical system files, install backdoors, alter configurations, or deploy malware on affected systems.
Availability (HIGH): Complete disruption of the affected service or system is possible, including denial of service, system crashes, or rendering the product inoperable.
Scope Unchanged: The vulnerability's scope is Unchanged (U), meaning exploitation is contained within the vulnerable component. The impact, while significant, is limited to the affected product environment itself.
With an EPSS score of 0.02417 (84.91th percentile), this vulnerability ranks among the most likely to be exploited in real-world attacks, underscoring the urgency of remediation.
Exploit Maturity
CVE-2021-28663 has confirmed active exploitation in the wild and is listed in CISA's Known Exploited Vulnerabilities catalog.
Exploit status: This vulnerability has been actively exploited, as confirmed by its inclusion in the KEV catalog. The EPSS score of 0.02417 (84.91th percentile) places it among the most exploited vulnerabilities tracked.
Ransomware association: As of the latest KEV data, no direct ransomware association has been confirmed for CVE-2021-28663. However, the confirmed exploitation in the wild means threat actors are actively using this vulnerability in attacks.
Attack surface: The vulnerability requires network access with low attack complexity and low privileges, requiring no user interaction. Organizations should assume exploitation tools exist and are being actively used by threat actors.
KEV deadline: CISA required federal agencies to remediate this vulnerability by 2021-11-17. All organizations should treat this deadline as a strong recommendation for their own remediation timelines.
Remediation
- Apply vendor patches immediately. Apply updates per vendor instructions. Consult the vendor advisory for specific patch guidance and updated versions.
- Verify affected product versions in your environment. Identify all instances of Arm Mali Graphics Processing Unit (GPU) in your infrastructure (affected versions: arm bifrost gpu kernel driver (>= r0p0, < r29p0), arm midgard gpu kernel driver (>= r4p0, < r31p0), arm valhall gpu kernel driver (>= r19p0, < r29p0)). Use asset inventory and vulnerability scanning tools to ensure no instances are missed.
- Implement interim mitigations if patching is delayed. If immediate patching is not feasible, apply network-level controls such as restricting access to the affected component, enabling enhanced logging, and monitoring for indicators of compromise.
- Scan for signs of prior exploitation. Given the confirmed active exploitation of this vulnerability, review system logs and security monitoring data for evidence of compromise. Conduct a thorough investigation if any suspicious activity is detected.
- Update detection signatures and monitoring rules. Ensure intrusion detection and prevention systems, endpoint detection tools, and SIEM rules are updated to detect exploitation attempts targeting CVE-2021-28663.
- Conduct a post-remediation review. After patching, verify the fix is effective and document the remediation actions taken. Update your vulnerability management records and assess whether any additional hardening measures are warranted.
Technical Details
CVE-2021-28663 is a HIGH-severity vulnerability in Arm Mali Graphics Processing Unit (GPU) that can be exploited remotely over the network without physical access. The attack complexity is low, meaning no specialized conditions or preparation are required beyond the attack prerequisites. Low-level privileges are required to initiate the attack. No user interaction is required, allowing for fully automated exploitation.
Technical mechanism: The Arm Mali GPU kernel driver allows privilege escalation or information disclosure because GPU memory operations are mishandled, leading to a use-after-free. This affects Bifrost r0p0 through r28p0 before r29p0, Valhall r19p0 through r28p0 before r29p0, and Midgard r4p0 through r30p0.
CVSS 3.1 vector analysis: The vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H reflects an Attack Vector of NETWORK, Attack Complexity of LOW, Privileges Required of LOW, User Interaction of NONE, Scope UNCHANGED, and impact ratings of HIGH/HIGH/HIGH for Confidentiality/Integrity/Availability respectively.
Frequently Asked Questions
Is CVE-2021-28663 being actively exploited?
Yes, CVE-2021-28663 is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. The EPSS score of 0.02417 (84.91th percentile) further indicates significant exploitation probability. Organizations should treat this as an urgent priority requiring immediate remediation.
What products are affected by CVE-2021-28663?
The affected products include arm bifrost gpu kernel driver (>= r0p0, < r29p0), arm midgard gpu kernel driver (>= r4p0, < r31p0), arm valhall gpu kernel driver (>= r19p0, < r29p0). Organizations running any of these versions should verify their exposure and prioritize remediation. Check vendor advisories for the complete and most current list of affected versions.
How do I fix CVE-2021-28663?
Apply updates per vendor instructions. Ensure all affected instances of Arm Mali Graphics Processing Unit (GPU) are identified using vulnerability scanning and asset management tools. If immediate patching is not possible, implement network-level mitigations and enhanced monitoring. After patching, verify the fix and scan for indicators of prior compromise.
How severe is CVE-2021-28663?
CVE-2021-28663 is rated HIGH with a CVSS 3.1 score of 8.8. Its EPSS score of 0.02417 places it in the 84.91th percentile for exploitation likelihood. The vulnerability has confirmed active exploitation in the wild and was required to be remediated by federal agencies by 2021-11-17 per CISA's KEV directive.
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