CVSS 3.1
8.1 highCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:HCVE-2021-27137
High (8.1) in DD-WRT DD-WRT. In CISA KEV since 2026-07-21. EPSS 4.0% chance of exploitation in the next 30 days.
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).
Severity
- EPSS
- 4.0% chance of exploitation in the next 30 days; higher than 90% of CVEs (scores of 2026-10-31)
- CISA KEV
- listed 2026-07-21, due 2026-07-24
- CWE
- CWE-121
- Published
- Modified
- Record from
- the NVD, synced
Affected
- dd-wrt:dd-wrt
References
- https://securityaffairs.com/193290/uncategorized/iot-botnet-c0xmo-adds-competitor-killing-capability.html
- https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/
- https://svn.dd-wrt.com/changeset/45724
- https://www.bleepingcomputer.com/news/security/c0xmo-botnet-spreads-via-dd-wrt-router-flaw-kills-rival-malware/
- https://www.fortinet.com/blog/threat-research/inside-cross-platform-propagation-of-new-gafgyt-variant-c0xmo