Local privilege escalation via unchecked stack write
Published Sep 7, 2026 · Updated Sep 8, 2026
Stack-based buffer overflow in Power HAL on affected MediaTek chipsets allows System-privileged local users to escalate privileges. The component writes beyond a stack buffer because it omits a bounds check, although MediaTek has not disclosed the affected function or input path. Exploitation requires an attacker already to hold System privilege, needs no user interaction, and remains limited to a local path.
Summary
What happened
Stack-based buffer overflow in Power HAL on affected MediaTek chipsets allows System-privileged local users to escalate privileges. The component writes beyond a stack buffer because it omits a bounds check, although MediaTek has not disclosed the affected function or input path. Exploitation requires an attacker already to hold System privilege, needs no user interaction, and remains limited to a local path.
The record
- CVE
- CVE-2026-20509
- Published
- Sep 7, 2026
- Updated
- Sep 8, 2026
- Vendor
- MediaTek
- Product
- MediaTek Chipset
- Classifications
- CWE-121, T1068
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- Sep 7, 2026CVE publishedPublication date reported by the CVE source.
- Sep 8, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=MT2718
- Affected versionversion=MT6739
- Affected versionversion=MT6761
- Affected versionversion=MT6765
- Affected versionversion=MT6768
- Affected versionversion=MT6769
- Affected versionversion=MT6781
- Affected versionversion=MT6789
- Affected versionversion=MT6833
- Affected versionversion=MT6835
- Affected versionversion=MT6853
- Affected versionversion=MT6855
- Affected versionversion=MT6858
- Affected versionversion=MT6877
- Affected versionversion=MT6878
- Affected versionversion=MT6879
- Affected versionversion=MT6881
- Affected versionversion=MT6883
- Affected versionversion=MT6885
- Affected versionversion=MT6886
- Affected versionversion=MT6889
- Affected versionversion=MT6893
- Affected versionversion=MT6895
- Affected versionversion=MT6897
- Affected versionversion=MT6899
- Affected versionversion=MT6983
- Affected versionversion=MT6985
- Affected versionversion=MT6989
- Affected versionversion=MT6991
- Affected versionversion=MT6993
- Affected versionversion=MT8171
- Affected versionversion=MT8186
- Affected versionversion=MT8188
- Affected versionversion=MT8189
- Affected versionversion=MT8196
- Affected versionversion=MT8668
- Affected versionversion=MT8676
- Affected versionversion=MT8678
- Affected versionversion=MT8696
- Affected versionversion=MT8793
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo