Risk Letters

Exploited vulnerability

CVE-2021-27137

TLP:CLEAR

DD-WRT Stack-Based Buffer Overflow Vulnerability

DD-WRT contains a stack-based buffer overflow vulnerability that could allow an unauthenticated attacker to overflow an internal buffer used by UPnP and trigger a code execution vulnerability.

Facts

  • Vendor: DD-WRT
  • Product: DD-WRT
  • CVSS: 8.1
  • EPSS (probability of exploitation within 30 days): 4 %
  • On CISA's Known Exploited Vulnerabilities list since: 21 July 2026
  • First known exploitation: 21 July 2026
  • CISA's deadline for US federal agencies: 24 July 2026
  • Weakness: CWE-121
  • First seen by Risk Letters: 21 July 2026

Members see which Nordic sectors the flaw hits, and what to do about it.

Get the full brief

Data: NVD (public domain), CISA KEV, FIRST EPSS, MITRE ATT&CK, AlienVault OTX. NVD