Remote privilege escalation via unchecked modem write
Published Apr 7, 2026 · Updated Apr 7, 2026
Out-of-bounds write in MediaTek chipset modems allows remote attackers to gain elevated privileges through a rogue base station. The modem processes untrusted base-station data without the required bounds check and writes beyond the intended memory boundary; MediaTek has not disclosed the specific routine or message. Exploitation requires the UE to connect to an attacker-controlled base station and requires user interaction, but no prior execution privileges.
Summary
What happened
Out-of-bounds write in MediaTek chipset modems allows remote attackers to gain elevated privileges through a rogue base station. The modem processes untrusted base-station data without the required bounds check and writes beyond the intended memory boundary; MediaTek has not disclosed the specific routine or message. Exploitation requires the UE to connect to an attacker-controlled base station and requires user interaction, but no prior execution privileges.
The record
- CVE
- CVE-2026-20433
- Published
- Apr 7, 2026
- Updated
- Apr 7, 2026
- Vendor
- MediaTek
- Product
- MediaTek Chipset
- Classifications
- CWE-787, T1203
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 7, 2026CVE publishedPublication date reported by the CVE source.
- Apr 7, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=MT2735
- Affected versionversion=MT2737
- Affected versionversion=MT6813
- Affected versionversion=MT6833
- Affected versionversion=MT6833P
- Affected versionversion=MT6835
- Affected versionversion=MT6835T
- Affected versionversion=MT6853
- Affected versionversion=MT6853T
- Affected versionversion=MT6855
- Affected versionversion=MT6855T
- Affected versionversion=MT6873
- Affected versionversion=MT6875
- Affected versionversion=MT6875T
- Affected versionversion=MT6877
- Affected versionversion=MT6877T
- Affected versionversion=MT6877TT
- Affected versionversion=MT6878
- Affected versionversion=MT6878M
- Affected versionversion=MT6879
- Affected versionversion=MT6880
- Affected versionversion=MT6883
- Affected versionversion=MT6885
- Affected versionversion=MT6886
- Affected versionversion=MT6889
- Affected versionversion=MT6890
- Affected versionversion=MT6891
- Affected versionversion=MT6893
- Affected versionversion=MT6895
- Affected versionversion=MT6895TT
- Affected versionversion=MT6896
- Affected versionversion=MT6897
- Affected versionversion=MT6899
- Affected versionversion=MT6980
- Affected versionversion=MT6980D
- Affected versionversion=MT6983
- Affected versionversion=MT6983T
- Affected versionversion=MT6985
- Affected versionversion=MT6985T
- Affected versionversion=MT6989
- Affected versionversion=MT6989T
- Affected versionversion=MT6990
- Affected versionversion=MT6991
- Affected versionversion=MT8668
- Affected versionversion=MT8673
- Affected versionversion=MT8675
- Affected versionversion=MT8676
- Affected versionversion=MT8678
- Affected versionversion=MT8755
- Affected versionversion=MT8771
- Affected versionversion=MT8775
- Affected versionversion=MT8791
- Affected versionversion=MT8791T
- Affected versionversion=MT8792
- Affected versionversion=MT8793
- Affected versionversion=MT8795T
- Affected versionversion=MT8797
- Affected versionversion=MT8798
- Affected versionversion=MT8863
- Affected versionversion=MT8873
- Affected versionversion=MT8883
- Affected versionversion=MT8893
What conditions does exploitation require?
What is affected?
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.
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
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Your stack
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