Vulnerability Monitor

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CVE-2021-35031


A vulnerability in the TFTP client of Zyxel GS1900 series firmware, XGS1210 series firmware, and XGS1250 series firmware, which could allow an authenticated LAN user to execute arbitrary OS commands via the GUI of the vulnerable device.


Security Impact Summary

This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 6.8, indicating it requires adjacent network access with relatively low complexity without requiring user interaction . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), and availability (service disruption) for affected systems. Impacting 28 products from zyxel, from zyxel, from zyxel and 25 others, organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2021, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.


Published

2021-12-28T11:15:07.463

Last Modified

2024-11-21T06:11:42.600

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 6.8 (MEDIUM)

CVSSv2 Vector

AV:A/AC:L/Au:S/C:C/I:C/A:C

  • Access Vector: ADJACENT_NETWORK
  • Access Complexity: LOW
  • Authentication: SINGLE
  • Confidentiality Impact: COMPLETE
  • Integrity Impact: COMPLETE
  • Availability Impact: COMPLETE
Exploitability Score

5.1

Impact Score

10.0

Weaknesses
  • Type: Secondary
    CWE-78
  • Type: Primary
    CWE-78

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Operating System zyxel gs1900-8_firmware < 2.70\(aahh.0\)-20211208 Yes
Hardware zyxel gs1900-8 - No
Operating System zyxel gs1900-8hp_firmware < 2.70\(aahi.0\)-20211208 Yes
Hardware zyxel gs1900-8hp - No
Operating System zyxel gs1900-10hp_firmware < 2.70\(aazi.0\)-20211208 Yes
Hardware zyxel gs1900-10hp - No
Operating System zyxel gs1900-16_firmware < 2.70\(aahj.0\)-20211208 Yes
Hardware zyxel gs1900-16 - No
Operating System zyxel gs1900-24e_firmware < 2.70\(aahk.0\)-20211208 Yes
Hardware zyxel gs1900-24e - No
Operating System zyxel gs1900-24ep_firmware < 2.70\(abto.0\)-20211208 Yes
Hardware zyxel gs1900-24ep - No
Operating System zyxel gs1900-24_firmware < 2.70\(aahl.0\)-20211208 Yes
Hardware zyxel gs1900-24 - No
Operating System zyxel gs1900-24hp_firmware < 2.70\(aahm.0\)-20211208 Yes
Hardware zyxel gs1900-24hp - No
Operating System zyxel gs1900-24hpv2_firmware < 2.70\(aatp.0\)-20211208 Yes
Hardware zyxel gs1900-24hpv2 - No
Operating System zyxel gs1900-48_firmware < 2.70\(aahn.0\)-20211208 Yes
Hardware zyxel gs1900-48 - No
Operating System zyxel gs1900-48hp_firmware < 2.70\(aaho.0\)-20211208 Yes
Hardware zyxel gs1900-48hp - No
Operating System zyxel gs1900-48hpv2_firmware < 2.70\(abtq.0\)-20211208 Yes
Hardware zyxel gs1900-48hpv2 - No
Operating System zyxel xgs1210-12_firmware < 1.00\(abty.5\)c0 Yes
Hardware zyxel xgs1210-12 - No
Operating System zyxel xgs1250-12_firmware < 1.00\(abwe.1\)c0 Yes
Hardware zyxel xgs1250-12 - No

References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For zyxel's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.