Home/CVE/A backdoor in certain Zyxel products allows remote TELNET access via a CGI script. This affects NAS520 V5.21(AASZ.4)C0,
CVE

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,

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, V5.20(ABAG.1)C0, and V5.21(ABAG.3)C0.

NSA325 v2_V4.81(AALS.0)C0 and V4.81(AAAJ.1)C0.

NSA310 4.22(AFK.0)C0 and 4.22(AFK.1)C0.

NAS326 V5.21(AAZF.8)C0, V5.11(AAZF.4)C0, V5.11(AAZF.2)C0, and V5.11(AAZF.3)C0.

NSA310S V4.75(AALH.2)C0.

NSA320S V4.75(AANV.2)C0 and V4.75(AANV.1)C0.

NSA221 V4.41(AFM.1)C0.

and NAS540 V5.21(AATB.5)C0 and V5.21(AATB.3)C0.

HIGH · CVSS 8.8 EPSS 0.00235
Schedule remediation
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
▤

Affected Products & Versions

4
zyxel nas326 firmware< v5.21\(aazf.9\)c0
zyxel nas520 firmware< v5.21\(aasz.5\)c0
zyxel nas540 firmware< v5.21\(aatb.6\)c0
zyxel nas542 firmware< v5.21\(abag.6\)c0
▣

Scoring & Timeline

8.8
HIGH · CVSS v3.1 · cve@mitre.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD06 Aug 2020 · 05:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://www.zyxel.com/support/Zyxel-security-advisory-for-NAS-remote-access-vulnerability.shtmlVendor Advisory
https://www.zyxel.com/us/en/support/security_advisories.shtmlVendor Advisory
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