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01 Record

CVE-2020-13364

A backdoor in certain Zyxel products allows remote TELNET access via a CGI script. This affects NAS520 V5.21(AASZ.4)C0, V5.21(AASZ.0)C0, V5.11(AASZ.3)C0, and V5.11(AASZ.0)C0; NAS542 V5.11(ABAG.0)C0,

MediumPUBLISHEDCNA: mitre
CNA base score6.5 CVSS v3.xCVSS:3.0/AC:L/AV:N/A:N/C:L/I:L/PR:N/S:U/UI:N

02 Description

A backdoor in certain Zyxel products allows remote TELNET access via a CGI script. This affects NAS520 V5.21(AASZ.4)C0, V5.21(AASZ.0)C0, V5.11(AASZ.3)C0, and V5.11(AASZ.0)C0; NAS542 V5.11(ABAG.0)C0,

03 Exploitation and scoring

Exploitation
Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.
SSVC decision
Not assessed by CISA
EPSS probability
1.15% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 66.8% of scored records. A rank, not a probability.
NVD base score
8.8 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD analysis status
Modified. NVD last modified this record on 2026-06-17.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2020-08-06 16:54Z6 YR AGO
Last updated
2024-08-04 12:18Z2 YR AGO
Reserved
2020-05-21
Assigning CNA
mitre
Record state
PUBLISHED
Severity
Medium (CVSS 6.5)
CNA CVSS vector
CVSS:3.0/AC:L/AV:N/A:N/C:L/I:L/PR:N/S:U/UI:N
Weaknesses
No CWE assigned
Data version
5.1
Document digest
b7c66d124954e439b9632c437b95f5bac02e040a39e1c7db3985a52d94ad5827

05 Affected products

VendorProductVersionsPlatforms
zyxelnas326Not specified—
zyxelnas326_firmwareNot specified—
zyxelnas520Not specified—
zyxelnas520_firmwareNot specified—
zyxelnas540Not specified—
zyxelnas540_firmwareNot specified—
zyxelnas542Not specified—
zyxelnas542_firmwareNot specified—

06 References