CVE Details
CVE-2021-27137
DD-WRT Stack-Based Buffer Overflow Vulnerability
Published: 2026-07-21
CVSS: 8.1 HIGH
Product: DD-WRT DD-WRT
Due Date: 2026-07-24
DD-WRT contains a stack-based buffer overflow vulnerability that could allow an unauthenticated attacker to overflow an internal buffer used by UPnP and trigger a code execution vulnerability.
GitHub PoC
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No GitHub PoC data.
FIRST EPSS
EPSS estimates the probability of exploitation in the next 30 days. Higher values indicate higher likelihood of real-world exploitation.
Timeline
CVE Stalker
KEV
MITRE
GitHub
FIRST (EPSS)
MITRE
CVSS
SSVC
References
Show Raw Data
| Key | Remaining Key | Value |
|---|---|---|
| dataType | CVE_RECORD | |
| cveMetadata > | state | PUBLISHED |
| cveMetadata > | cveId | CVE-2021-27137 |
| cveMetadata > | assignerOrgId | 8254265b-2729-46b6-b9e3-3dfca2d5bfca |
| cveMetadata > | assignerShortName | mitre |
| cveMetadata > | dateUpdated | 2026-07-22T03:55:45.793Z |
| cveMetadata > | dateReserved | 2021-02-10T00:00:00.000Z |
| cveMetadata > | datePublished | 2026-07-16T00:00:00.000Z |
| containers > | cna > affected > 0 > defaultStatus | unaffected |
| containers > | cna > affected > 0 > product | DD-WRT |
| containers > | cna > affected > 0 > vendor | DD-WRT |
| containers > | cna > affected > 0 > versions > 0 > lessThan | 45724 |
| containers > | cna > affected > 0 > versions > 0 > status | affected |
| containers > | cna > affected > 0 > versions > 0 > version | 0 |
| containers > | cna > affected > 0 > versions > 0 > versionType | custom |
| containers > | cna > descriptions > 0 > lang | en |
| containers > | cna > descriptions > 0 > 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). |
| containers > | cna > metrics > 0 > cvssV3_1 > attackComplexity | HIGH |
| containers > | cna > metrics > 0 > cvssV3_1 > attackVector | NETWORK |
| containers > | cna > metrics > 0 > cvssV3_1 > availabilityImpact | HIGH |
| containers > | cna > metrics > 0 > cvssV3_1 > baseScore | 8.1 |
| containers > | cna > metrics > 0 > cvssV3_1 > baseSeverity | HIGH |
| containers > | cna > metrics > 0 > cvssV3_1 > confidentialityImpact | HIGH |
| containers > | cna > metrics > 0 > cvssV3_1 > integrityImpact | HIGH |
| containers > | cna > metrics > 0 > cvssV3_1 > privilegesRequired | NONE |
| containers > | cna > metrics > 0 > cvssV3_1 > scope | UNCHANGED |
| containers > | cna > metrics > 0 > cvssV3_1 > userInteraction | NONE |
| containers > | cna > metrics > 0 > cvssV3_1 > vectorString | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
| containers > | cna > metrics > 0 > cvssV3_1 > version | 3.1 |
| containers > | cna > metrics > 0 > format | CVSS |
| containers > | cna > metrics > 0 > scenarios > 0 > lang | en |
| containers > | cna > metrics > 0 > scenarios > 0 > value | GENERAL |
| containers > | cna > problemTypes > 0 > descriptions > 0 > cweId | CWE-121 |
| containers > | cna > problemTypes > 0 > descriptions > 0 > description | CWE-121 Stack-based Buffer Overflow |
| containers > | cna > problemTypes > 0 > descriptions > 0 > lang | en |
| containers > | cna > problemTypes > 0 > descriptions > 0 > type | CWE |
| containers > | cna > providerMetadata > orgId | 8254265b-2729-46b6-b9e3-3dfca2d5bfca |
| containers > | cna > providerMetadata > shortName | mitre |
| containers > | cna > providerMetadata > dateUpdated | 2026-07-16T17:38:47.947Z |
| containers > | cna > references > 0 > url | https://svn.dd-wrt.com/changeset/45724 |
| containers > | cna > references > 1 > url | https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/ |
| containers > | cna > references > 2 > url | https://securityaffairs.com/193290/uncategorized/iot-botnet-c0xmo-adds-competitor-killing-capability.html |
| containers > | cna > references > 3 > url | https://www.bleepingcomputer.com/news/security/c0xmo-botnet-spreads-via-dd-wrt-router-flaw-kills-rival-malware/ |
| containers > | cna > references > 4 > url | https://www.fortinet.com/blog/threat-research/inside-cross-platform-propagation-of-new-gafgyt-variant-c0xmo |
| containers > | cna > x_generator > engine | enrichogram 0.0.1 |
| containers > | cna > cpeApplicability > 0 > nodes > 0 > operator | OR |
| containers > | cna > cpeApplicability > 0 > nodes > 0 > negate | False |
| containers > | cna > cpeApplicability > 0 > nodes > 0 > cpeMatch > 0 > vulnerable | True |
| containers > | cna > cpeApplicability > 0 > nodes > 0 > cpeMatch > 0 > criteria | cpe:2.3:a:dd-wrt:dd-wrt:*:*:*:*:*:*:*:* |
| containers > | cna > cpeApplicability > 0 > nodes > 0 > cpeMatch > 0 > versionEndExcluding | 45724 |
| containers > | adp > 0 > metrics > 0 > other > type | ssvc |
| containers > | adp > 0 > metrics > 0 > other > content > timestamp | 2026-07-21T00:00:00+00:00 |
| containers > | adp > 0 > metrics > 0 > other > content > options > 0 > Exploitation | active |
| containers > | adp > 0 > metrics > 0 > other > content > options > 1 > Automatable | no |
| containers > | adp > 0 > metrics > 0 > other > content > options > 2 > Technical Impact | total |
| containers > | adp > 0 > metrics > 0 > other > content > role | CISA Coordinator |
| containers > | adp > 0 > metrics > 0 > other > content > version | 2.0.3 |
| containers > | adp > 0 > metrics > 0 > other > content > id | CVE-2021-27137 |
| containers > | adp > 0 > metrics > 1 > other > type | kev |
| containers > | adp > 0 > metrics > 1 > other > content > dateAdded | 2026-07-21 |
| containers > | adp > 0 > metrics > 1 > other > content > reference | https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27137 |
| containers > | adp > 0 > references > 0 > url | https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/ |
| containers > | adp > 0 > references > 0 > tags > 0 | exploit |
| containers > | adp > 0 > references > 1 > url | https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27137 |
| containers > | adp > 0 > references > 1 > tags > 0 | government-resource |
| containers > | adp > 0 > title | CISA ADP Vulnrichment |
| containers > | adp > 0 > providerMetadata > orgId | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
| containers > | adp > 0 > providerMetadata > shortName | CISA-ADP |
| containers > | adp > 0 > providerMetadata > dateUpdated | 2026-07-22T03:55:45.793Z |
| containers > | adp > 0 > timeline > 0 > time | 2026-07-21T00:00:00.000Z |
| containers > | adp > 0 > timeline > 0 > lang | en |
| containers > | adp > 0 > timeline > 0 > value | CVE-2021-27137 added to CISA KEV |
| dataVersion | 5.2 |