CVE-2021-47854Public exploitNetwork attack vector

UPnP service crash via unbounded UUID copy

Published Jan 21, 2026 · Updated Jan 21, 2026

Classic buffer overflow in DD-WRT 45723 allows remote attackers on the local network to crash UPnP with a crafted M-SEARCH packet. In ssdp.c, an unbounded copy writes an attacker-controlled UUID from the packet into a 128-byte internal buffer. UPnP must be enabled, is disabled by default, and listens only on internal interfaces; code execution depends on device-specific mitigations.

CVSS severity8.7
High
EPSS probability1.04%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Classic buffer overflow in DD-WRT 45723 allows remote attackers on the local network to crash UPnP with a crafted M-SEARCH packet. In ssdp.c, an unbounded copy writes an attacker-controlled UUID from the packet into a 128-byte internal buffer. UPnP must be enabled, is disabled by default, and listens only on internal interfaces; code execution depends on device-specific mitigations.

The record

CVE
CVE-2021-47854
Published
Jan 21, 2026
Updated
Jan 21, 2026
Vendor
DD-WRT
Product
DD-WRT
Classifications
CWE-120, T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=45723

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

DD-WRT · DD-WRTversion=45723

Published CVSS scores

8.7VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
9.8VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1210Exploitation of Remote Services

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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