CVE-2021-29256
. 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.
- CVSS
- 8.8Highscored by CISA
- Exploited in the wild
- Yes, in CISA KEV since 7 Jul 2023CISA deadline for US federal agencies: 28 Jul 2023
- EPSS
- 3.0%chance of exploitation in the next 30 daystop 13% of scored CVEsFIRST score of 11 Nov 2026
- Fix
- Patch availablesee the advisories in the references
- Published
- 24 May 2021analysed here 12 Nov 2026
Do first. Apply updates per vendor instructions or discontinue use of the product if updates are unavailable. (CISA's required action for this KEV entry)
Summary
Triage
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 a use-after-free memory 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 7 Jul 2023.
- CISA due date
- 28 Jul 2023, the remediation deadline for US federal agencies
- CISA required action
- Apply updates per vendor instructions or discontinue use of the product if updates are unavailable.
- Public exploit code
- None on record in Exploit-DB, Metasploit, Nuclei templates or PoC-in-GitHub.
- CISA SSVC
- exploitation active, automatable no, technical impact totalAssessed by CISA 4 Feb 2025 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.
Timeline
- 24 May 2021Published
- 7 Jul 2023Added to CISA KEV (exploited in the wild)773 days (about 2 years) later
- 28 Jul 2023CISA remediation due date (US federal agencies)21 days later
- 4 Feb 2025CISA SSVC assessment: exploitation active558 days (about 2 years) later
- 21 Oct 2025CVE record last updated259 days (about 9 months) later
- 12 Nov 2026Analysed by vulneraibility.com387 days (about 1 year) 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-2021-29256 being exploited?
Yes. CVE-2021-29256 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-2021-29256?
CVE-2021-29256 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-2021-29256?
Yes. A fix has been recorded for CVE-2021-29256. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2021-29256 affect?
CVE-2021-29256 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
2 references in the CVE record, grouped by the tags the record gives them.
Other links (2)
- developer.arm.com /support/arm-security-updates/mali-gpu-kernel-driver
- cisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-29256
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
Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.
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