CVE-2021-27137

HIGH

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).

CVSS v3.1 Score

8.1
HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Published: 7/16/2026Modified: 7/22/2026

Related Intelligence (0)

No articles currently reference this CVE.

References (7)

https://securityaffairs.com/193290/uncategorized/iot-botnet-c0xmo-adds-competitor-killing-capability.htmlExploitThird Party Advisoryhttps://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/ExploitThird Party Advisoryhttps://svn.dd-wrt.com/changeset/45724Patchhttps://www.bleepingcomputer.com/news/security/c0xmo-botnet-spreads-via-dd-wrt-router-flaw-kills-rival-malware/ExploitThird Party Advisoryhttps://www.fortinet.com/blog/threat-research/inside-cross-platform-propagation-of-new-gafgyt-variant-c0xmoExploithttps://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/ExploitThird Party Advisoryhttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27137US Government Resource