What is CVE-2021-47854?

CVE-2021-47854 is a critical-severity vulnerability in Embedd Gmbh Dd-Wrt, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2026-01-21.

How severe is CVE-2021-47854?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Buffer overflow in Embedd Gmbh Dd-Wrt

CVE-2021-47854

DD-WRT version 45723 contains a buffer overflow vulnerability in the UPNP network discovery service that allows remote attackers to potentially execute arbitrary code. Attackers can send crafted M-SEARCH packets with oversized UUID payloads to trigger buffer overflow conditions on the target device.

Vulnerability class: Buffer Overflow

EPSS: 0.010 (58.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Embedd Gmbh Dd-wrt — versions 45723

Weakness classification (CWE)

CWE-120 — Buffer Copy without Checking Size of Input (Classic Buffer Overflow)

References

ExploitDB-49730 (exploit)
DD-WRT Official Vendor Homepage (product)
DD-WRT Software Download Repository (product)
SSD Security Advisory for DD-WRT UPNP Buffer Overflow (technical-description)
VulnCheck Advisory: DD-WRT 45723 - UPNP Buffer Overflow (third-party-advisory)

Frequently asked questions

What is CVE-2021-47854?: CVE-2021-47854 is a critical-severity vulnerability in Embedd Gmbh Dd-Wrt, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2026-01-21.
How severe is CVE-2021-47854?: Critical severity. CVSS v3 base score is 9.8 out of 10.