{"id":"CVE-2021-27137","aliases":[],"url":"https://o3.security/vulnerability/CVE-2021-27137","summary":"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…","details":"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":"2026-07-16T18:16:39.113","modified":"2026-07-22T05:17:07.330","cvss":{"score":8.1,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"},"epss":{"score":0.03995,"percentile":0.89752,"asOf":"2026-08-26"},"cisaKev":{"dateAdded":"2026-07-21","dueDate":"2026-07-24","knownRansomwareCampaignUse":false},"exploitsKnown":0,"affectedPackages":[],"fix":null,"references":[{"type":"EXPLOIT","url":"https://securityaffairs.com/193290/uncategorized/iot-botnet-c0xmo-adds-competitor-killing-capability.html"},{"type":"EXPLOIT","url":"https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/"},{"type":"FIX","url":"https://svn.dd-wrt.com/changeset/45724"},{"type":"EXPLOIT","url":"https://www.bleepingcomputer.com/news/security/c0xmo-botnet-spreads-via-dd-wrt-router-flaw-kills-rival-malware/"},{"type":"EXPLOIT","url":"https://www.fortinet.com/blog/threat-research/inside-cross-platform-propagation-of-new-gafgyt-variant-c0xmo"},{"type":"EXPLOIT","url":"https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/"},{"type":"WEB","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27137"}],"provenance":{"sources":["OSV.dev","NVD","CISA KEV","FIRST.org (EPSS)"],"lastVerified":"2026-07-22T05:17:07.330"}}