HOMEVULNERABILITIESCVE-2020-24355
CRITICAL

CVE-2020-24355

CWE-732Published: September 2, 2020· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official Description

Zyxel VMG5313-B30B router on firmware 5.13(ABCJ.6)b3_1127, and possibly older versions of firmware are affected by insecure permissions which allows regular and other users to create new users with elevated privileges. This is done by changing "FirstIndex" field in JSON that is POST-ed during account creation. Similar may also be possible with account deletion.

NVD Source

Technical Analysis

CVE-2020-24355 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.

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

zyxel2 product(s)
vmg5313-b30b firmwarevmg5313-b30b
Source: NVD CPE · 2 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://blog.somegeneric.ninja/Zyxel_VMG5153_B30B
ADVISORYhttps://blog.somegeneric.ninja/Zyxel_VMG5153_B30B_part2
ADVISORYhttps://www.zyxel.com/support/security_advisories.shtml
ADVISORYhttps://blog.somegeneric.ninja/Zyxel_VMG5153_B30B
ADVISORYhttps://blog.somegeneric.ninja/Zyxel_VMG5153_B30B_part2
ADVISORYhttps://www.zyxel.com/support/security_advisories.shtml

All References (6)

→
https://blog.somegeneric.ninja/Zyxel_VMG5153_B30BExploit · Third Party Advisory
→
https://blog.somegeneric.ninja/Zyxel_VMG5153_B30B_part2Exploit · Third Party Advisory
→
https://www.zyxel.com/support/security_advisories.shtmlVendor Advisory
→
https://blog.somegeneric.ninja/Zyxel_VMG5153_B30BExploit · Third Party Advisory
→
https://blog.somegeneric.ninja/Zyxel_VMG5153_B30B_part2Exploit · Third Party Advisory
→
https://www.zyxel.com/support/security_advisories.shtmlVendor Advisory

Quick Facts

CVE IDCVE-2020-24355
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-732
CISA KEVNo
Affected1 vendor(s)
PublishedSep 2, 2020

Related CVEs (CWE-732)

CVE-2025-12004
10.0
CVE-2026-9508
10.0
CVE-2014-125121
10.0
CVE-2025-69426
10.0
CVE-2025-14988
10.0
CVE-2024-5618
9.9

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2020-24355 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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