HOMEVULNERABILITIESCVE-2020-25014
CRITICAL

CVE-2020-25014

CWE-787Published: November 27, 2020· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official Description

A stack-based buffer overflow in fbwifi_continue.cgi on Zyxel UTM and VPN series of gateways running firmware version V4.30 through to V4.55 allows remote unauthenticated attackers to execute arbitrary code via a crafted http packet.

NVD Source

Technical Analysis

CVE-2020-25014 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

From a weakness classification perspective (CWE-787): Out-of-bounds write vulnerabilities can lead to data corruption, crashes, or arbitrary code execution.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

zyxel52 product(s)
zldzywall 110zywall 1100zywall 310usg 110usg 1100usg 1900usg 20wusg 20w-vpnusg 2200-vpnusg 310usg 40+40
Source: NVD CPE · 54 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://businessforum.zyxel.com/categories/security-news-and-release
ADVISORYhttps://www.zyxel.com/support/Zyxel-security-advisory-for-buffer-overflow-vulnerability.shtml
ADVISORYhttps://businessforum.zyxel.com/categories/security-news-and-release
ADVISORYhttps://www.zyxel.com/support/Zyxel-security-advisory-for-buffer-overflow-vulnerability.shtml

All References (4)

→
https://businessforum.zyxel.com/categories/security-news-and-releaseRelease Notes · Vendor Advisory
→
https://www.zyxel.com/support/Zyxel-security-advisory-for-buffer-overflow-vulnerability.shtmlVendor Advisory
→
https://businessforum.zyxel.com/categories/security-news-and-releaseRelease Notes · Vendor Advisory
→
https://www.zyxel.com/support/Zyxel-security-advisory-for-buffer-overflow-vulnerability.shtmlVendor Advisory

Quick Facts

CVE IDCVE-2020-25014
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-787
CISA KEVNo
Affected1 vendor(s)
PublishedNov 27, 2020

Related CVEs (CWE-787)

CVE-2015-5105
10.0
CVE-2015-5098
10.0
CVE-2004-0978
10.0
CVE-2012-3957
10.0
CVE-2015-5096
10.0
CVE-2018-17160
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2020-25014 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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