CVE-2021-27239 - CVE House
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Status published High CVE-2021-27239

This vulnerability allows network-adjacent attackers to execute arbitrary code on...

Vulnerability Description

This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of NETGEAR R6400 and R6700 firmware version 1.0.4.98 routers. Authentication is not required to exploit this vulnerability. The specific flaw exists within the upnpd service, which listens on UDP port 1900 by default. A crafted MX header field in an SSDP message can trigger an overflow of a fixed-length stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of root. Was ZDI-CAN-11851.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:

  • Anonymous

References

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Affected Vendor

Affected Software

Multiple Routers
Vulnerable Versions:
firmware version 1.0.4.98

Timeline

Official Publish: March 29th, 2021
Last Modified: August 3rd, 2024
Added to House: July 21st, 2026

CVSS Vectors

V3: CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weaknesses (CWE)

CWE-121

MITRE ATT&CK TTPs

T1190 Exploit Public-Facing Application
Initial Access
T1068 Exploitation for Privilege Escalation
Privilege Escalation
T1055 Process Injection
Defense Evasion
T1105 Ingress Tool Transfer
Command and Control
T1485 Data Destruction
Impact