{"id":"CVE-2021-27137","state":"PUBLISHED","title":"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 re","description":"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).","publishedAt":"2026-07-16T00:00:00.000Z","updatedAt":"2026-07-22T03:55:45.793Z","severity":{"score":8.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"mitre"},"assigner":"mitre","products":["DD-WRT DD-WRT"],"affected":[{"vendor":"DD-WRT","product":"DD-WRT","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"45724","versionType":"custom"}]}],"references":["https://svn.dd-wrt.com/changeset/45724","https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/","https://securityaffairs.com/193290/uncategorized/iot-botnet-c0xmo-adds-competitor-killing-capability.html","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","https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27137"],"weaknesses":["CWE-121"],"ingestedAt":"2026-10-29T19:48:15.637Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2021/27xxx/CVE-2021-27137.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-27137","state":"PUBLISHED","datePublished":"2026-07-16T00:00:00.000Z","dateUpdated":"2026-07-22T03:55:45.793Z","assignerShortName":"mitre","assignerOrgId":"8254265b-2729-46b6-b9e3-3dfca2d5bfca","dateReserved":"2021-02-10T00:00:00.000Z"},"containers":{"cna":{"descriptions":[{"lang":"en","value":"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)."}],"affected":[{"vendor":"DD-WRT","product":"DD-WRT","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"45724","versionType":"custom"}]}],"references":[{"url":"https://svn.dd-wrt.com/changeset/45724"},{"url":"https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/"},{"url":"https://securityaffairs.com/193290/uncategorized/iot-botnet-c0xmo-adds-competitor-killing-capability.html"},{"url":"https://www.bleepingcomputer.com/news/security/c0xmo-botnet-spreads-via-dd-wrt-router-flaw-kills-rival-malware/"},{"url":"https://www.fortinet.com/blog/threat-research/inside-cross-platform-propagation-of-new-gafgyt-variant-c0xmo"}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":8.1,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-121","description":"CWE-121 Stack-based Buffer Overflow","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"mitre","orgId":"8254265b-2729-46b6-b9e3-3dfca2d5bfca","dateUpdated":"2026-07-16T17:38:47.947Z"},"x_generator":{"engine":"enrichogram 0.0.1"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:dd-wrt:dd-wrt:*:*:*:*:*:*:*:*","versionEndExcluding":"45724"}]}]}]},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/","tags":["exploit"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27137","tags":["government-resource"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-21T00:00:00+00:00","options":[{"Exploitation":"active"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3","id":"CVE-2021-27137"}}},{"other":{"type":"kev","content":{"dateAdded":"2026-07-21","reference":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27137"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-22T03:55:45.793Z"},"timeline":[{"time":"2026-07-21T00:00:00.000Z","lang":"en","value":"CVE-2021-27137 added to CISA KEV"}]}]}}}