# CVE-2026-20477: MediaTek display out-of-bounds write

Source: https://junglewise.ai/threats/cve-2026-20477-mediatek-display-out-of-bounds-write  
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-2026-20477 · Severity: medium · CVSS 6 · Published 2026-08-03

MediaTek chipsets include a display driver component that processes graphics rendering requests. A missing bounds check in this driver allows a privileged attacker to write data outside allocated memory, potentially corrupting the kernel and gaining full system control. This could affect millions of smartphones, tablets, and IoT devices powered by MediaTek processors.

Technologies: [MediaTek Dimensity 5G](https://junglewise.ai/threats/technologies/dimensity-5g), [MediaTek Mt6991](https://junglewise.ai/threats/technologies/mt6991), [MediaTek Mt6991 Firmware](https://junglewise.ai/threats/technologies/mt6991-firmware), [MediaTek MT6993](https://junglewise.ai/threats/technologies/mt6993), [MediaTek Mt6993 Firmware](https://junglewise.ai/threats/technologies/mt6993-firmware), [MediaTek Mt8188](https://junglewise.ai/threats/technologies/mt8188), [MediaTek Mt8188 Firmware](https://junglewise.ai/threats/technologies/mt8188-firmware), [MediaTek Mt8189](https://junglewise.ai/threats/technologies/mt8189), [MediaTek Mt8189 Firmware](https://junglewise.ai/threats/technologies/mt8189-firmware), [MediaTek Mt8668](https://junglewise.ai/threats/technologies/mt8668), [MediaTek Mt8668 Firmware](https://junglewise.ai/threats/technologies/mt8668-firmware), [MediaTek MT8676](https://junglewise.ai/threats/technologies/mt8676), [MediaTek Mt8676 Firmware](https://junglewise.ai/threats/technologies/mt8676-firmware), [MediaTek MT8678](https://junglewise.ai/threats/technologies/mt8678), [MediaTek Mt8678 Firmware](https://junglewise.ai/threats/technologies/mt8678-firmware), [MediaTek Mt8781](https://junglewise.ai/threats/technologies/mt8781), [MediaTek Mt8781 Firmware](https://junglewise.ai/threats/technologies/mt8781-firmware), [MediaTek Mt8799](https://junglewise.ai/threats/technologies/mt8799), [MediaTek Mt8799 Firmware](https://junglewise.ai/threats/technologies/mt8799-firmware), [MediaTek Mt8910](https://junglewise.ai/threats/technologies/mt8910), [MediaTek Mt8910 Firmware](https://junglewise.ai/threats/technologies/mt8910-firmware). Vendors: [MediaTek](https://junglewise.ai/threats/vendors/mediatek).

## Quick answers

**Is CVE-2026-20477 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-20477 being exploited in the wild.

**How severe is CVE-2026-20477?** Medium severity, with a CVSS score of 6, published 3 August 2026.

**Which products and versions are affected?** MediaTek Dimensity 5G.

**Is there a fix for CVE-2026-20477?** 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-2026-20477 attacked?** It is attacked with local access.

**Am I affected by CVE-2026-20477?** Check whether you run MediaTek Dimensity 5G, MediaTek Mt6991, MediaTek Mt6991 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

The vulnerability is a out-of-bounds write (CWE-787) in the display subsystem caused by missing bounds validation. The flaw requires an attacker to already hold System privilege, meaning this is a local privilege escalation or privilege-boundary bypass vulnerability. No user interaction is required for exploitation once System access is obtained. An attacker can corrupt kernel memory or other privileged processes, potentially achieving kernel-level code execution. A patch is available; MediaTek identified this as Issue MSV-7658 with Patch ID ALPS11009963.

## Affected products

- MediaTek Dimensity 5G

## Timeline

- 2026-08-03: disclosed
- 2026-08-03: advisory: MediaTek Product Security Bulletin August 2026

## References

- [https://www.mediatek.com/product-security-bulletin/August-2026](https://www.mediatek.com/product-security-bulletin/August-2026)

## Related threats

- [MediaTek ip_stack out of bounds read in 5G modem](https://junglewise.ai/threats/cve-2026-68590-in-ip-stack-there-is-a-possible-out-of-bounds-read-due-to)
- [MediaTek GPU pdma privilege escalation due to missing permission check](https://junglewise.ai/threats/cve-2026-20591-in-gpu-pdma-there-is-a-possible-escalation-of-privilege-due-to-a)
- [MediaTek display system crash due to logic error](https://junglewise.ai/threats/cve-2026-20590-in-display-there-is-a-possible-system-crash-due-to-a-logic-error)
- [MediaTek USB use-after-free denial of service](https://junglewise.ai/threats/cve-2026-20583-in-usb-there-is-a-possible-system-crash-due-to-use-after-free)
- [MediaTek USB driver double free memory corruption](https://junglewise.ai/threats/cve-2026-20582-in-usb-there-is-a-possible-memory-corruption-due-to-double-free)