CVE-2021-27137

{"id": "CVE-2021-27137", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2021-27137", "role": "CISA Coordinator", "options": [{"exploitation": "active"}, {"automatable": "no"}, {"technicalImpact": "total"}], "version": "2.0.3", "timestamp": "2026-07-21T00:00:00+00:00"}}], "cvssMetricV31": [{"type": "Secondary", "source": "cve@mitre.org", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 8.1, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "HIGH", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 2.2}]}, "affected": [{"source": "cve@mitre.org", "affectedData": [{"vendor": "DD-WRT", "product": "DD-WRT", "versions": [{"status": "affected", "version": "0", "lessThan": "45724", "versionType": "custom"}], "defaultStatus": "unaffected"}]}], "published": "2026-07-16T18:16:39.113", "references": [{"url": "https://securityaffairs.com/193290/uncategorized/iot-botnet-c0xmo-adds-competitor-killing-capability.html", "tags": ["Exploit", "Third Party Advisory"], "source": "cve@mitre.org"}, {"url": "https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/", "tags": ["Exploit", "Third Party Advisory"], "source": "cve@mitre.org"}, {"url": "https://svn.dd-wrt.com/changeset/45724", "tags": ["Patch"], "source": "cve@mitre.org"}, {"url": "https://www.bleepingcomputer.com/news/security/c0xmo-botnet-spreads-via-dd-wrt-router-flaw-kills-rival-malware/", "tags": ["Exploit", "Third Party Advisory"], "source": "cve@mitre.org"}, {"url": "https://www.fortinet.com/blog/threat-research/inside-cross-platform-propagation-of-new-gafgyt-variant-c0xmo", "tags": ["Exploit"], "source": "cve@mitre.org"}, {"url": "https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/", "tags": ["Exploit", "Third Party Advisory"], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}, {"url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27137", "tags": ["US Government Resource"], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "cve@mitre.org", "description": [{"lang": "en", "value": "CWE-121"}]}], "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)."}], "lastModified": "2026-07-22T05:17:07.330", "cisaActionDue": "2026-07-24", "cisaExploitAdd": "2026-07-21", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:dd-wrt:dd-wrt:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "69D9E341-F731-4BA7-9410-8EEBA216CBCA", "versionEndExcluding": "45724"}], "operator": "OR"}]}], "sourceIdentifier": "cve@mitre.org", "cisaRequiredAction": "Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA\u2019s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA\u2019s \u201cForensics Triage Requirements\u201d (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.", "cisaVulnerabilityName": "DD-WRT Stack-Based Buffer Overflow Vulnerability"}