CVE-2021-35395
Published: November 3, 2021
Official Description
Realtek AP-Router SDK HTTP web server boa contains a buffer overflow vulnerability due to unsafe copies of some overly long parameters submitted in the form that lead to denial-of-service (DoS).
CISA KEV Advisory
Realtek AP-Router SDK Buffer Overflow Vulnerability
Realtek AP-Router SDK HTTP web server boa contains a buffer overflow vulnerability due to unsafe copies of some overly long parameters submitted in the form that lead to denial-of-service (DoS).
Apply updates per vendor instructions.
Risk Analysis
The Realtek AP-Router SDK HTTP web server boa contains a buffer overflow vulnerability. This flaw can be triggered by overly long parameters, leading to a denial-of-service condition. The high EPSS score of 0.93663 suggests a significant likelihood of exploitation, and its presence in the KEV confirms active exploitation.
This vulnerability is actively being exploited in the wild. The flaw is remotely exploitable and can lead to denial-of-service.
Apply available security updates for Realtek AP-Router SDK. Implement input validation and consider network-level protections to filter malformed requests.
Technical Analysis
CVE-2021-35395 requires local access, meaning attackers must already have a foothold on the target system.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
CISA has added CVE-2021-35395 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.
Exploit & PoC Resources
All References (1)
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-35395 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
- !CISA KEV: Federal agencies must patch per BOD 22-01 timeline
- !Active exploitation confirmed — treat as P1