What is CVE-2026-20477?

CVE-2026-20477 is a medium-severity vulnerability in Mediatek Mt6991 Firmware, classified under Out-of-bounds Write. CVSS score: 6.0/10. Published 2026-08-03.

How severe is CVE-2026-20477?

Medium severity. CVSS v3 base score is 6.0 out of 10.

Buffer overflow in Mediatek Mt6991 Firmware

CVE-2026-20477

In display, there is a possible out of bounds write due to a missing bounds check. This could lead to local escalation of privilege if a malicious actor has already obtained the System privilege. User interaction is not needed for exploitation. Patch ID: ALPS11009963; Issue ID: MSV-7658.

Vulnerability class: Buffer Overflow

EPSS: 0.001 (2.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.0 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N.

Affected products

Mediatek Mt6991_firmware
Mediatek Mt6993_firmware
Mediatek Mt8188_firmware
Mediatek Mt8189_firmware
Mediatek Mt8668_firmware
Mediatek Mt8676_firmware
Mediatek Mt8678_firmware
Mediatek Mt8781_firmware
Mediatek Mt8799_firmware
Mediatek Mt8910_firmware

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

security@mediatek.com (Vendor Advisory)

Frequently asked questions

What is CVE-2026-20477?: CVE-2026-20477 is a medium-severity vulnerability in Mediatek Mt6991 Firmware, classified under Out-of-bounds Write. CVSS score: 6.0/10. Published 2026-08-03.
How severe is CVE-2026-20477?: Medium severity. CVSS v3 base score is 6.0 out of 10.