CVE•Published 2026-07-16•Modified 2026-07-22•1 article on news•5 live references•NVD data

CVE-2021-27137Dd-wrt · Dd-wrt

Vulnerability data via NVD (ingested)

CVSS v3.1

8.1

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS percentile

Exploit Prediction Scoring System · top 8% of all CVEs

Weaknesses (CWE)

CWE-121Stack-based Buffer Overflow

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).

Timeline

Published 2026-07-16

Modified 2026-07-22

External references

NVD MITRE Exploit-DB trickest/cve VulnCheck

Search for exposed instances

Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).

Shodan · vuln tag7 hosts

vuln:CVE-2021-27137

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · OS

os:"Dd-wrt"

Hosts Shodan identified as running Dd-wrt.

More intel sources (5)

Shodan report

vuln:CVE-2021-27137

Country / ASN / product breakdown for the vuln query.

Censys

vulnerabilities.cve_id: CVE-2021-27137