# CVE-2026-20479: MediaTek Modem out-of-bounds read due to missing bounds check Source: https://junglewise.ai/threats/cve-2026-20479-mediatek-modem-out-of-bounds-read-due-to-missing-bounds-check Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats Published: 2026-08-03. Updated: 2026-09-25 License: CC BY 4.0 with a link back CVE-2026-20479 · Severity: high · CVSS 7.5 · Published 2026-08-03 MediaTek's modem component, which handles cellular connectivity in smartphones and IoT devices, contains a flaw that allows remote attackers to trigger a denial-of-service condition. An attacker controlling a rogue cellular base station can exploit this vulnerability without requiring any special privileges or user interaction, potentially disrupting device connectivity and communications. Technologies: [MediaTek Modem](https://junglewise.ai/threats/technologies/modem), [MediaTek MT2735](https://junglewise.ai/threats/technologies/mt2735), [MediaTek Mt2735 Firmware](https://junglewise.ai/threats/technologies/mt2735-firmware), [MediaTek MT6833](https://junglewise.ai/threats/technologies/mt6833), [MediaTek Mt6833 Firmware](https://junglewise.ai/threats/technologies/mt6833-firmware), [MediaTek Mt6853](https://junglewise.ai/threats/technologies/mt6853), [MediaTek Mt6853 Firmware](https://junglewise.ai/threats/technologies/mt6853-firmware), [MediaTek Mt6855](https://junglewise.ai/threats/technologies/mt6855), [MediaTek Mt6855 Firmware](https://junglewise.ai/threats/technologies/mt6855-firmware), [MediaTek MT6873](https://junglewise.ai/threats/technologies/mt6873), [MediaTek Mt6873 Firmware](https://junglewise.ai/threats/technologies/mt6873-firmware), [MediaTek Mt6875](https://junglewise.ai/threats/technologies/mt6875), [MediaTek Mt6875 Firmware](https://junglewise.ai/threats/technologies/mt6875-firmware), [MediaTek Mt6877](https://junglewise.ai/threats/technologies/mt6877), [MediaTek Mt6877 Firmware](https://junglewise.ai/threats/technologies/mt6877-firmware), [MediaTek Mt6880](https://junglewise.ai/threats/technologies/mt6880), [MediaTek Mt6880 Firmware](https://junglewise.ai/threats/technologies/mt6880-firmware), [MediaTek Mt6883](https://junglewise.ai/threats/technologies/mt6883), [MediaTek Mt6883 Firmware](https://junglewise.ai/threats/technologies/mt6883-firmware), [MediaTek Mt6885](https://junglewise.ai/threats/technologies/mt6885), [MediaTek Mt6885 Firmware](https://junglewise.ai/threats/technologies/mt6885-firmware), [MediaTek Mt6889](https://junglewise.ai/threats/technologies/mt6889), [MediaTek Mt6889 Firmware](https://junglewise.ai/threats/technologies/mt6889-firmware), [MediaTek Mt6890](https://junglewise.ai/threats/technologies/mt6890), [MediaTek Mt6890 Firmware](https://junglewise.ai/threats/technologies/mt6890-firmware), [MediaTek MT6891](https://junglewise.ai/threats/technologies/mt6891), [MediaTek Mt6891 Firmware](https://junglewise.ai/threats/technologies/mt6891-firmware), [MediaTek Mt6893](https://junglewise.ai/threats/technologies/mt6893), [MediaTek Mt6893 Firmware](https://junglewise.ai/threats/technologies/mt6893-firmware), [MediaTek Mt8675](https://junglewise.ai/threats/technologies/mt8675), [MediaTek Mt8675 Firmware](https://junglewise.ai/threats/technologies/mt8675-firmware), [MediaTek Mt8771](https://junglewise.ai/threats/technologies/mt8771), [MediaTek Mt8771 Firmware](https://junglewise.ai/threats/technologies/mt8771-firmware), [MediaTek MT8791](https://junglewise.ai/threats/technologies/mt8791), [MediaTek Mt8791 Firmware](https://junglewise.ai/threats/technologies/mt8791-firmware), [MediaTek Mt8791t](https://junglewise.ai/threats/technologies/mt8791t), [MediaTek Mt8791t Firmware](https://junglewise.ai/threats/technologies/mt8791t-firmware), [MediaTek Mt8797](https://junglewise.ai/threats/technologies/mt8797), [MediaTek Mt8797 Firmware](https://junglewise.ai/threats/technologies/mt8797-firmware). Vendors: [MediaTek](https://junglewise.ai/threats/vendors/mediatek). ## Quick answers **Is CVE-2026-20479 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-20479 being exploited in the wild. **How severe is CVE-2026-20479?** High severity, with a CVSS score of 7.5, published 3 August 2026. **Which products and versions are affected?** MediaTek Modem. **Is there a fix for CVE-2026-20479?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it. **How is CVE-2026-20479 attacked?** It is attacked over the network, in device firmware. **Am I affected by CVE-2026-20479?** Check whether you run MediaTek Modem, MediaTek MT2735, MediaTek Mt2735 Firmware or one of the others listed. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you. ## Technical details This vulnerability is an out-of-bounds read in MediaTek's modem firmware caused by a missing bounds check. The flaw exists in modem processing logic that handles cellular base station communications. An attacker can exploit this by operating a rogue 5G or 4G base station and transmitting a specially crafted message to a victim device connected to the malicious station. The out-of-bounds read can cause a crash or undefined behavior in the modem, leading to denial of service. MediaTek has released patches via security bulletin (Patch ID: MOLY00741071) with fixes available to OEMs. ## Affected products - MediaTek Modem ## Timeline - 2026-08-03: disclosed - 2026-08-03: advisory: MediaTek Product Security Bulletin published ## References - [https://www.mediatek.com/product-security-bulletin/August-2026](https://www.mediatek.com/product-security-bulletin/August-2026) ## Related threats - [MediaTek Modem privilege escalation via permissions bypass](https://junglewise.ai/threats/cve-2026-68591-in-modem-there-is-a-possible-escalation-of-privilege-due-to-a) - [MediaTek Modem out-of-bounds write privilege escalation](https://junglewise.ai/threats/cve-2026-68589-in-modem-there-is-a-possible-out-of-bounds-write-due-to-a-missing) - [MediaTek Modem integer overflow denial of service](https://junglewise.ai/threats/cve-2026-68588-in-modem-there-is-a-possible-way-for-xxx-to-xxxxx-due-to-an) - [MediaTek Modem logic error denial of service](https://junglewise.ai/threats/cve-2026-20600-in-modem-there-is-a-possible-application-crash-due-to-a-logic) - [MediaTek Modem privilege escalation due to missing permission check](https://junglewise.ai/threats/cve-2026-20599-in-modem-there-is-a-possible-escalation-of-privilege-due-to-a)