Device crash via missing modem bounds check
Published Sep 7, 2026 · Updated Sep 7, 2026
Reachable assertion in the MediaTek Chipset modem allows physically proximate attackers to crash a connected device through a rogue base station. The modem fails to bounds-check attacker-controlled input before reaching an assertion, causing the system to crash. Exploitation requires the user equipment to connect to an attacker-controlled base station, but requires no privileges or user interaction and interrupts availability without reported data exposure or modification.
Summary
What happened
Reachable assertion in the MediaTek Chipset modem allows physically proximate attackers to crash a connected device through a rogue base station. The modem fails to bounds-check attacker-controlled input before reaching an assertion, causing the system to crash. Exploitation requires the user equipment to connect to an attacker-controlled base station, but requires no privileges or user interaction and interrupts availability without reported data exposure or modification.
The record
- CVE
- CVE-2026-20503
- Published
- Sep 7, 2026
- Updated
- Sep 7, 2026
- Vendor
- MediaTek
- Product
- MediaTek Chipset
- Classifications
- CWE-617, T1499
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 7, 2026CVE publishedPublication date reported by the CVE source.
- Sep 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=MT2716
- Affected versionversion=MT2735
- Affected versionversion=MT2737
- Affected versionversion=MT6813
- Affected versionversion=MT6833
- Affected versionversion=MT6835
- Affected versionversion=MT6853
- Affected versionversion=MT6855
- Affected versionversion=MT6858
- Affected versionversion=MT6873
- Affected versionversion=MT6875
- Affected versionversion=MT6877
- Affected versionversion=MT6878
- Affected versionversion=MT6879
- Affected versionversion=MT6880
- Affected versionversion=MT6881
- 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=MT6896
- Affected versionversion=MT6897
- Affected versionversion=MT6899
- Affected versionversion=MT6980
- Affected versionversion=MT6982VB
- Affected versionversion=MT6983
- Affected versionversion=MT6985
- Affected versionversion=MT6986
- Affected versionversion=MT6988
- Affected versionversion=MT6989
- Affected versionversion=MT6990
- Affected versionversion=MT6991
- Affected versionversion=MT6993
- 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=MT8796
- 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?
Published CVSS scores
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.
Public exploit references
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Technologies
Your stack
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Your stack
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