What’s Vulnerable › Vulnerabilities

CVE-2021-42911

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 3.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2022-03-29 · updated 2026-06-17
• Weakness: CWE-134

Description

A Format String vulnerability exists in DrayTek Vigor 2960 <= 1.5.1.3, DrayTek Vigor 3900 <= 1.5.1.3, and DrayTek Vigor 300B <= 1.5.1.3 in the mainfunction.cgi file via a crafted HTTP message containing malformed QUERY STRING, which could let a remote malicious user execute arbitrary code.

Affected products

• DrayTek Vigor2960: through 1.5.1.3
• DrayTek Vigor 300B: through 1.5.1.3
• DrayTek Vigor3900 Firmware: through 1.5.1.3

References

• https://gist.github.com/Cossack9989/e9c1c2d2e69b773ca4251acdd77f2835
• https://gist.github.com/Cossack9989/e9c1c2d2e69b773ca4251acdd77f2835

Get alerted when CVE-2021-42911 or the next vulnerability affects your stack