CVE-2021-27137
An issue was discovered in router/upnp/src/ssdp.c in DD-WRT before 45724. An unsafe strcpy in the UPnP handling functionality allows an unauthenticated remote attacker to send a request that would overflow an internal fixed buffer. Exploitation requires the DD-WRT user to enable UPnP (which is off by default, and only listens on internal interfaces by default). This occurs in ssdp_msearch (reachable by an M-SEARCH request).
- Published Jul 16, 2026
- CVSS 8.1 high
- 4.0% chance of exploitation in the next 30 days (EPSS)
- In CISA's Known Exploited Vulnerabilities catalog
- Public exploit code is available
- A fix is available