CVE-2020-14993Known exploitationPublic exploitNetwork attack vector

Unauthenticated code execution via unchecked CGI parameter

Published Jun 23, 2020 · Updated Aug 4, 2024

Stack-based buffer overflow in DrayTek Vigor2960, Vigor3900, and Vigor300B before 1.5.1.1 allows remote attackers to execute code. The unauthenticated authusersms action in mainfunction.cgi copies the formuserphonenumber POST value into a fixed-size stack buffer without enforcing its length. Network access to the device web interface is sufficient; an oversized value corrupts the stack and permits control of the appliance.

CVSS severity9.8
Critical
EPSS probability5.33%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in DrayTek Vigor2960, Vigor3900, and Vigor300B before 1.5.1.1 allows remote attackers to execute code. The unauthenticated authusersms action in mainfunction.cgi copies the formuserphonenumber POST value into a fixed-size stack buffer without enforcing its length. Network access to the device web interface is sufficient; an oversized value corrupts the stack and permits control of the appliance.

The record

CVE
CVE-2020-14993
Published
Jun 23, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 12, 2020Exploitation reportedDrayTek report of possible exploitation
  2. Jun 23, 2020CVE publishedPublication date reported by the CVE source.
  3. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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