CVE-2020-14993

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 5.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2020-06-23 · updated 2026-06-17
Weakness: CWE-787

Description

A stack-based buffer overflow on DrayTek Vigor2960, Vigor3900, and Vigor300B devices before 1.5.1.1 allows remote attackers to execute arbitrary code via the formuserphonenumber parameter in an authusersms action to mainfunction.cgi.

Affected products

DrayTek Vigor2960: before 1.5.1.1 — fixed in 1.5.1.1
DrayTek Vigor 300B: before 1.5.1.1 — fixed in 1.5.1.1
DrayTek Vigor3900 Firmware: before 1.5.1.1 — fixed in 1.5.1.1

How to fix

Upgrade to a fixed version: DrayTek Vigor2960 1.5.1.1; DrayTek Vigor 300B 1.5.1.1; DrayTek Vigor3900 Firmware 1.5.1.1. Check the vendor advisory for mitigations.

References

https://github.com/dexterone/Vigor-poc
https://www.draytek.com/about/security-advisory
https://www.draytek.com/about/security-advisory/vigor3900-/-vigor2960-/-vigor300b-stack-based-buffer-overflow-vulnerability-%28cve-2020-14473%29
https://github.com/dexterone/Vigor-poc
https://www.draytek.com/about/security-advisory
https://www.draytek.com/about/security-advisory/vigor3900-/-vigor2960-/-vigor300b-stack-based-buffer-overflow-vulnerability-%28cve-2020-14473%29

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