CVE-2021-27137
- State
- Published
- Severity
- 8.1 High
- Published
- Jul 16, 2026
- Updated
- Jul 22, 2026
- Reserved
- Feb 10, 2021
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).
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 8.1 High | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H | mitre |
Weaknesses
- CWE-121 Stack-based Buffer Overflow
Affected Products
| Product | Versions |
|---|---|
DD-WRTDD-WRT |
|
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-2021-27137government-resource
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