CVE-2020-9054

CRITICALNVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score elevated to 9.8 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2022-03-25), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 9.8 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — 4 sources updated this weekExploited in the wild
9.8
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS: 100%CVSS: 9.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Multiple ZyXEL network-attached storage (NAS) devices running firmware version 5.21 contain a pre-authentication command injection vulnerability, which may allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable device. ZyXEL NAS devices achieve authentication by using the weblogin.cgi CGI executable. This program fails to properly sanitize the username parameter that is passed to it. If the username parameter contains certain characters, it can allow command injection with the privileges of the web server that runs on the ZyXEL device. Although the web server does not run as the root user, ZyXEL devices include a setuid utility that can be leveraged to run any command with root privileges. As such, it should be assumed that exploitation of this vulnerability can lead to remote code execution with root privileges. By sending a specially-crafted HTTP POST or GET request to a vulnerable ZyXEL device, a remote, unauthenticated attacker may be able to execute arbitrary code on the device. This may happen by directly connecting to a device if it is directly exposed to an attacker. However, there are ways to trigger such crafted requests even if an attacker does not have direct connectivity to a vulnerable devices. For example, simply visiting a website can result in the compromise of any ZyXEL device that is reachable from the client system. Affected products include: NAS326 before firmware V5.21(AAZF.7)C0 NAS520 before firmware V5.21(AASZ.3)C0 NAS540 before firmware V5.21(AATB.4)C0 NAS542 before firmware V5.21(ABAG.4)C0 ZyXEL has made firmware updates available for NAS326, NAS520, NAS540, and NAS542 devices. Affected models that are end-of-support: NSA210, NSA220, NSA220+, NSA221, NSA310, NSA310S, NSA320, NSA320S, NSA325 and NSA325v2

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
84(Attend)
EG Risk 84/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation100% × 40%
Automatability0% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS
100.0%
KEV
⚠ Exploited

Published

March 4, 2020

Last Modified

November 10, 2025

Advisory Details (5)

Auto-updated Jun 1, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: cert.
generic

Support Download Page Redirect

https://www.zyxel.com/support/remote-code-execution-vulnerability-of-NAS-products.shtml
generic Patch Available🔴 Active Exploitation

Zyxel Fixes 0day in Network Storage Devices – Krebs on Security

https://krebsonsecurity.com/2020/02/zyxel-fixes-0day-in-network-storage-devices/
cert

VU#498544 - ZyXEL pre-authentication command injection in weblogin.cgi

https://kb.cert.org/vuls/id/498544/
cert
https://kb.cert.org/artifacts/cve-2020-9054.html
generic🔴 Active Exploitation

CWE - CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') (4.20)

https://cwe.mitre.org/data/definitions/78.html

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 40× in last 7d / 196× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 368 total refreshes for this CVE.

  1. 2026-07-24 14:15 UTCEPSS rescore
  2. 2026-07-23 01:55 UTCEG score recompute
  3. 2026-07-22 23:22 UTCEG score recompute
  4. 2026-07-22 23:22 UTCGHSA enrichment
  5. 2026-07-22 22:41 UTCEG score recompute
  6. 2026-07-22 19:40 UTCCISA KEV update
  7. 2026-07-22 19:33 UTCGHSA enrichment
  8. 2026-07-22 15:44 UTCGHSA enrichment
  9. 2026-07-22 11:55 UTCGHSA enrichment
  10. 2026-07-22 08:07 UTCGHSA enrichment
  11. 2026-07-22 04:16 UTCGHSA enrichment
  12. 2026-07-22 00:21 UTCGHSA enrichment
  13. 2026-07-21 19:44 UTCGHSA enrichment
  14. 2026-07-21 15:52 UTCGHSA enrichment
  15. 2026-07-21 14:37 UTCCISA KEV update
  16. 2026-07-21 12:04 UTCGHSA enrichment
  17. 2026-07-21 08:17 UTCGHSA enrichment
  18. 2026-07-21 04:29 UTCGHSA enrichment
  19. 2026-07-21 00:41 UTCGHSA enrichment
  20. 2026-07-20 20:53 UTCGHSA enrichment
  21. 2026-07-20 17:04 UTCGHSA enrichment
  22. 2026-07-20 13:14 UTCGHSA enrichment
  23. 2026-07-20 09:26 UTCGHSA enrichment
  24. 2026-07-20 05:38 UTCGHSA enrichment
  25. 2026-07-20 01:51 UTCGHSA enrichment
Show 75 more
  1. 2026-07-19 22:03 UTCGHSA enrichment
  2. 2026-07-19 18:15 UTCGHSA enrichment
  3. 2026-07-19 14:27 UTCGHSA enrichment
  4. 2026-07-19 10:39 UTCGHSA enrichment
  5. 2026-07-19 06:50 UTCGHSA enrichment
  6. 2026-07-19 03:01 UTCGHSA enrichment
  7. 2026-07-18 23:13 UTCGHSA enrichment
  8. 2026-07-18 19:25 UTCGHSA enrichment
  9. 2026-07-18 15:37 UTCGHSA enrichment
  10. 2026-07-18 11:49 UTCGHSA enrichment
  11. 2026-07-18 08:01 UTCGHSA enrichment
  12. 2026-07-18 04:13 UTCGHSA enrichment
  13. 2026-07-18 00:24 UTCGHSA enrichment
  14. 2026-07-17 20:36 UTCGHSA enrichment
  15. 2026-07-17 16:48 UTCGHSA enrichment
  16. 2026-07-17 12:59 UTCGHSA enrichment
  17. 2026-07-17 09:11 UTCEG score recompute
  18. 2026-07-17 09:11 UTCGHSA enrichment
  19. 2026-07-17 05:23 UTCGHSA enrichment
  20. 2026-07-17 01:35 UTCGHSA enrichment
  21. 2026-07-16 21:47 UTCGHSA enrichment
  22. 2026-07-16 17:59 UTCGHSA enrichment
  23. 2026-07-16 17:04 UTCCISA KEV update
  24. 2026-07-16 14:11 UTCGHSA enrichment
  25. 2026-07-16 10:23 UTCGHSA enrichment
  26. 2026-07-16 06:35 UTCGHSA enrichment
  27. 2026-07-16 02:45 UTCGHSA enrichment
  28. 2026-07-15 22:57 UTCGHSA enrichment
  29. 2026-07-15 19:09 UTCGHSA enrichment
  30. 2026-07-15 16:49 UTCCISA KEV update
  31. 2026-07-15 15:21 UTCGHSA enrichment
  32. 2026-07-15 15:04 UTCCISA KEV update
  33. 2026-07-15 11:31 UTCGHSA enrichment
  34. 2026-07-15 07:43 UTCGHSA enrichment
  35. 2026-07-15 03:55 UTCGHSA enrichment
  36. 2026-07-15 00:07 UTCGHSA enrichment
  37. 2026-07-14 20:17 UTCGHSA enrichment
  38. 2026-07-14 18:05 UTCCISA KEV update
  39. 2026-07-14 16:28 UTCGHSA enrichment
  40. 2026-07-14 12:40 UTCGHSA enrichment
  41. 2026-07-14 08:52 UTCGHSA enrichment
  42. 2026-07-14 05:04 UTCGHSA enrichment
  43. 2026-07-14 01:16 UTCGHSA enrichment
  44. 2026-07-13 21:28 UTCGHSA enrichment
  45. 2026-07-13 17:40 UTCGHSA enrichment
  46. 2026-07-13 17:07 UTCCISA KEV update
  47. 2026-07-13 13:52 UTCGHSA enrichment
  48. 2026-07-13 10:04 UTCGHSA enrichment
  49. 2026-07-13 06:05 UTCGHSA enrichment
  50. 2026-07-13 02:16 UTCGHSA enrichment
  51. 2026-07-12 22:28 UTCGHSA enrichment
  52. 2026-07-12 18:40 UTCGHSA enrichment
  53. 2026-07-12 14:51 UTCGHSA enrichment
  54. 2026-07-12 11:02 UTCGHSA enrichment
  55. 2026-07-12 07:13 UTCGHSA enrichment
  56. 2026-07-12 03:25 UTCGHSA enrichment
  57. 2026-07-11 23:37 UTCGHSA enrichment
  58. 2026-07-11 19:49 UTCGHSA enrichment
  59. 2026-07-11 16:01 UTCGHSA enrichment
  60. 2026-07-11 12:13 UTCGHSA enrichment
  61. 2026-07-11 08:25 UTCGHSA enrichment
  62. 2026-07-11 04:37 UTCGHSA enrichment
  63. 2026-07-11 00:49 UTCGHSA enrichment
  64. 2026-07-10 21:01 UTCGHSA enrichment
  65. 2026-07-10 17:52 UTCCISA KEV update
  66. 2026-07-10 17:13 UTCGHSA enrichment
  67. 2026-07-10 13:24 UTCGHSA enrichment
  68. 2026-07-10 09:34 UTCGHSA enrichment
  69. 2026-07-10 05:46 UTCGHSA enrichment
  70. 2026-07-10 01:58 UTCGHSA enrichment
  71. 2026-07-09 22:09 UTCGHSA enrichment
  72. 2026-07-09 18:21 UTCGHSA enrichment
  73. 2026-07-09 14:34 UTCGHSA enrichment
  74. 2026-07-09 10:44 UTCGHSA enrichment
  75. 2026-07-09 06:55 UTCGHSA enrichment

Publicly available exploits

(2 references)

Working exploit code is in the public domain (1 GitHub PoC). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCdarrenmartyn/CVE-2020-9054
    First seen Sep 9, 2021

    CVE-2020-9054 PoC for Zyxel

    Open source ↗
  • Nucleihttp/cves/2020/CVE-2020-9054.yaml
    First seen Jan 1, 2020

    Zyxel NAS Firmware 5.21- Remote Code Execution

    Open source ↗

Related CVEs(same CWE)

Frequently asked(6)

What is CVE-2020-9054?
CVE-2020-9054 is a critical vulnerability published on March 4, 2020. Multiple ZyXEL network-attached storage (NAS) devices running firmware version 5.21 contain a pre-authentication command injection vulnerability, which may allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable device. ZyXEL NAS devices achieve authentication by using…
When was CVE-2020-9054 disclosed?
CVE-2020-9054 was first published in the National Vulnerability Database on March 4, 2020, with the most recent update on November 10, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-9054 actively exploited?
Yes. CISA added CVE-2020-9054 to the Known Exploited Vulnerabilities catalog on March 25, 2022, affecting Zyxel Multiple Network-Attached Storage (NAS) Devices. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2020-9054?
CVE-2020-9054 has a CVSS v3 base score of 9.8 (NVD).
Which products are affected by CVE-2020-9054?
CVE-2020-9054 affects Zyxel Multiple Network-Attached Storage (NAS) Devices. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2020-9054?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-9054, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2020-9054

Explore →

Is Your Infrastructure Affected by CVE-2020-9054?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs