CVE-2021-27137

Published Jul 16, 2026 CVSS 3.1 · 8.1 High EPSS 4.0% KEV · Listed
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).

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Title DD-WRT UPnP Buffer Overflow Allows Remote Code Execution
Type Values Removed Values Added
Title DD-WRT UPnP Buffer Overflow Allows Remote Code Execution
Type Values Removed Values Added
Title DD‑WRT UPnP Buffer Overflow Vulnerability
Type Values Removed Values Added
Title DD‑WRT UPnP Buffer Overflow Vulnerability
Type Values Removed Values Added
References
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'active', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Metrics kev

{'dateAdded': '2026-07-21T00:00:00+00:00', 'dueDate': '2026-07-24T00:00:00+00:00'}

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
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).
First Time appeared Dd-wrt
Dd-wrt dd-wrt
Weaknesses CWE-121
CPEs cpe:2.3:a:dd-wrt:dd-wrt:*:*:*:*:*:*:*:*
Vendors & Products Dd-wrt
Dd-wrt dd-wrt
References
Metrics cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
mitre
Published
Updated
Jul 22, 2026, 3:55 AM
Reserved
Feb 10, 2021, 12:00 AM
Status
Analyzed
Published
Jul 16, 2026, 6:16 PM
Modified
Jul 22, 2026, 5:17 AM