CVE-2020-13364

highpriority · track · 35EPSS 0.012 · 67 %ileEUUS

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

1.15% (67th) EPSS

CVSS 9 · high

Is it mine?

5 products

Check your exposure

Who says so?

3 sources

cnnvd · enisa_euvd · nvd

EPSS · scored 2026-10-27

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.

cvss

Technical severity, 0–10. One row per scoring source.

9.0

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.5–9

v2.09highAV:N/AC:L/Au:S/C:C/I:C/A:Cprimary · NVD / NIST USexploitability 8 · impact 10

v3.18.8highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 2.8 · impact 5.9

v3.06.5mediumCVSS:3.0/AC:L/AV:N/A:N/C:L/I:L/PR:N/S:U/UI:Nsecondary · ENISA EU

v3.06.5mediumCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:Nsecondary · cve@mitre.org USexploitability 3.9 · impact 2.5

v3.18.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-287USLLM-inferred

affected products (5)

Products and version ranges known to be affected.

n/a n/a≤ n/aenisa_euvdEU
zyxel nas326 firmware< v5.21\(aazf.9\)c0nvdUScpe:2.3:o:zyxel:nas326_firmware:*:*:*:*:*:*:*:*
zyxel nas520 firmware< v5.21\(aasz.5\)c0nvdUScpe:2.3:o:zyxel:nas520_firmware:*:*:*:*:*:*:*:*
zyxel nas540 firmware< v5.21\(aatb.6\)c0nvdUScpe:2.3:o:zyxel:nas540_firmware:*:*:*:*:*:*:*:*
zyxel nas542 firmware< v5.21\(abag.6\)c0nvdUScpe:2.3:o:zyxel:nas542_firmware:*:*:*:*:*:*:*:*

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd nvd NVD CVE.org MITRE

published 2020-08-06modified 2026-06-17

references (7)

External citations — patches, advisories, analysis.

scry

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