CVE-2021-28664

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.

CVSS: 8.8Highscored by CISA
Exploited in the wild: Yes, in CISA KEV since 3 Nov 2021CISA deadline for US federal agencies: 17 Nov 2021unvetted proof-of-concept code on github
EPSS: 5.5%chance of exploitation in the next 30 daystop 8% of scored CVEsFIRST score of 11 Nov 2026
Fix: Patch availablesee the advisories in the references
Published: 10 May 2021analysed here 12 Nov 2026

Do first. Apply updates per vendor instructions. (CISA's required action for this KEV entry)

Summary

Triage

Attack surface: Server-side
Exploitable: At runtime
Attack vector: network
Weakness: CWE-787 Out-of-Bounds Write
Can a WAF block it?: No. See why

The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.

Affected products

Products named in our analysis

arm:bifrost_gpu_kernel_driver
arm:midgard_gpu_kernel_driver
arm:valhall_gpu_kernel_driver

Fix and mitigation

WAF and other mitigations

Can a WAF block it? No. This is an out-of-bounds write, a memory-corruption bug. Generic WAF rules do not recognise the input that triggers it; only a rule written for this specific CVE can, and only if the triggering request has a recognisable shape.

Also consider: patch

Based on the weakness type only; no CVE-specific evidence yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.

Remediation steps (AI-written)

Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.

Exploitation evidence

CISA KEV catalog: Listed since 3 Nov 2021.
CISA due date: 17 Nov 2021, the remediation deadline for US federal agencies
CISA required action: Apply updates per vendor instructions.
Public exploit code: Unvetted proof-of-concept code on GitHub: 1 GitHub proof of concept
CISA SSVC: exploitation active, automatable no, technical impact totalAssessed by CISA 3 Feb 2025 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.

GitHub proofs of concept

woaphone/CVE-2021-28664-PoC2 stars

Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.

Timeline

10 May 2021Published
3 Nov 2021Added to CISA KEV (exploited in the wild)176 days (about 6 months) later
17 Nov 2021CISA remediation due date (US federal agencies)14 days later
3 Feb 2025CISA SSVC assessment: exploitation active1,175 days (about 3 years) later
21 Oct 2025CVE record last updated260 days (about 9 months) later
12 Sept 2026First proof-of-concept repository on GitHub (unvetted)325 days (about 11 months) later
12 Nov 2026Analysed by vulneraibility.com62 days (about 2 months) later

CVSS vector

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

Metric	Value	What it means
Attack vector	NetworkReachable over the internet or any routable network.	Reachable over the internet or any routable network.
Attack complexity	LowRepeatable attack, no special conditions.	Repeatable attack, no special conditions.
Privileges required	LowThe attacker needs basic user privileges.	The attacker needs basic user privileges.
User interaction	NoneNo victim action needed.	No victim action needed.
Scope	UnchangedImpact stays within the vulnerable component.	Impact stays within the vulnerable component.
Confidentiality	HighTotal data disclosure possible.	Total data disclosure possible.
Integrity	HighComplete modification possible.	Complete modification possible.
Availability	HighFull outage possible.	Full outage possible.

Common questions

Is CVE-2021-28664 being exploited?

Yes. CVE-2021-28664 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.

How severe is CVE-2021-28664?

CVE-2021-28664 is rated High with a CVSS score of 8.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2021-28664?

Yes. A fix has been recorded for CVE-2021-28664. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2021-28664 affect?

CVE-2021-28664 affects arm:bifrost_gpu_kernel_driver, arm:midgard_gpu_kernel_driver, arm:valhall_gpu_kernel_driver. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

References

NVD CVE.org CVE Details Source

4 references in the CVE record, grouped by the tags the record gives them.

Where the data on this page comes from

CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
NVD: CVSS and CPE data
CISA KEV catalog: exploitation, date added, due date
CISA Vulnrichment (ADP): SSVC decision points
FIRST EPSS: exploit probability and percentile
PoC-in-GitHub: GitHub repositories that claim a proof of concept

Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.

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