Name: CVE-2021-27137: Stack-based Buffer Overflow
Creator: Rapid7
Published: 2026-07-16T00:00:00.000Z
License: https://www.rapid7.com/legal/website-terms-of-use/
Keywords: CVE, CVE-2021-27137, CWE-121, Exploited in the Wild, CISA KEV Exploit, CVSS 8.1, EPSS 0.03995, CISA KEV

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 Details

CVSS 3.1 Base Score: 8.1
CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H)

Covered by Rapid7

Product	Vendor Advisory	Solution File	Added	Published
Dd Wrt	—	Upgrade DD-WRT to revision 45724 or later	Aug 3, 2026	Mar 15, 2021

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CVSS Details

Covered by Rapid7

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