Cyber Resilience

CVE-2021-29256

Memory Safety in Arm Bifrost Gpu Kernel Driver r16p0 – r30p0

CISA KEVActive ExploitationEUVD ExploitedMemory Safety
Published
24 May 2021
Modified
03 November 2025
KEV Added
07 July 2023
Patch / advisory
View advisory
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.030 86th percentile
Risk Priority 90 floored blend · peak EPSS

Summary

CVE-2021-29256 is a high-severity Use After Free (CWE-416) vulnerability in Arm Bifrost Gpu Kernel Driver. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked in the top 14% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

The vulnerability is a use-after-free flaw, identified as CWE-416, in the Arm Mali GPU kernel driver. It permits an unprivileged user to access freed memory and affects Bifrost GPU drivers from r16p0 through r29p0 (prior to r30p0), Valhall drivers from r19p0 through r29p0 (prior to r30p0), and Midgard drivers from r28p0 through r30p0. The issue carries a CVSS 3.1 base score of 8.8.

An attacker with low privileges can exploit the flaw over a network-accessible path without user interaction, resulting in information disclosure or escalation to root privileges on affected systems.

Arm has published security updates addressing the Mali GPU kernel driver, and the vulnerability appears in CISA's catalog of known exploited vulnerabilities in the wild.

EU & UK References

Vulnerability Data

. 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…

more

Midgard r28p0 through r30p0.

CWE(s)
CWE-416
KEV Date Added
07 July 2023

Related Threats

MITRE ATT&CK Enterprise Techniques

T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2021-28663Same product: Arm Bifrost Gpu Kernel Driverboth on KEV
CVE-2022-38181Same product: Arm Bifrost Gpu Kernel Driverboth on KEV
CVE-2023-4211Same product: Arm Bifrost Gpu Kernel Driverboth on KEV
CVE-2024-4610Same product: Arm Bifrost Gpu Kernel Driverboth on KEV
CVE-2023-6143Same product: Arm Bifrost Gpu Kernel Driver
CVE-2023-6241Same product: Arm Bifrost Gpu Kernel Driver
CVE-2024-0671Same product: Arm Bifrost Gpu Kernel Driver
CVE-2023-5249Same product: Arm Bifrost Gpu Kernel Driver
CVE-2024-3655Same product: Arm Bifrost Gpu Kernel Driver
CVE-2025-0427Same product: Arm Bifrost Gpu Kernel Driver

Affected Assets

arm
bifrost gpu kernel driver
r16p0 — r30p0
arm
midgard gpu kernel driver
r28p0 — r31p0
arm
valhall gpu kernel driver
r19p0 — r30p0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 3 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V1.4.3

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-16 Memory Protection
addresses: CWE-416

Use-after-free exploits that achieve arbitrary code execution are blocked or significantly hardened by non-executable pages and ASLR.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly incorporate memory-safety tooling and reviews that prevent most use-after-free defects.

ID.RA-01 partial match
prevents

Vulnerability identification processes can discover use-after-free issues via scanning or analysis but do not prevent their introduction.

PR.PS-02 partial match
prevents

Routine patching removes known use-after-free instances after they have been introduced in released software.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development can detect use-after-free bugs before release.

A.8.25 Secure development life cycle partial match
prevents

Secure SDLC mandates memory-safety practices that reduce use-after-free defects.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify memory-management rules that mitigate use-after-free.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles include memory-safety design choices that limit use-after-free exposure.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly prescribe avoidance of use-after-free patterns.

A.8.32 Change management partial match
prevents

Change-management processes help ensure memory-safety fixes are deployed consistently.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (1 rule)
  • V-248592 OL 8 must clear memory when it is freed to prevent use-after-free attacks. prevents CWE-416
RHEL 8 (1 rule)
  • V-230279 RHEL 8 must clear memory when it is freed to prevent use-after-free attacks. prevents CWE-416
RHEL 9 (1 rule)
  • V-257794 RHEL 9 must clear memory when it is freed to prevent use-after-free attacks. prevents CWE-416

References