CVE-2021-27137: DD-WRT Stack-Based Buffer Overflow Vulnerability
Summary
A stack-based buffer overflow vulnerability has been identified in DD-WRT, potentially allowing unauthenticated attackers to execute code. CISA mandates applying vendor-provided mitigations by July 24, 2026, with specific guidance for cloud services and a recommendation to discontinue use if mitigations are unavailable.
IFF Assessment
This vulnerability allows for code execution by an unauthenticated attacker, posing a direct threat to system integrity and confidentiality.
Severity
The vulnerability is a stack-based buffer overflow leading to code execution, which is a critical impact. The attack vector is network-based, and it is likely exploitable without privileges.
CISA KEV: Listed as actively exploited. Federal patch due: July 24, 2026. Known ransomware use: Unknown.
Defender Context
This vulnerability affects widely used firmware for routers, presenting a significant risk for network compromise. Defenders should prioritize applying vendor patches and ensure systems are configured securely, especially those with internet exposure, to prevent potential exploitation and ransomware deployment.