CVE-2021-29462Network attack vector

Data exfiltration via unchecked Host header

Published Apr 20, 2021 · Updated Aug 3, 2024

DNS rebinding in libupnp before 1.14.6 allows remote attackers to trigger local UPnP actions through a victim browser. The embedded HTTP server accepts any Host header, allowing a DNS-rebinding site to reach services as if requests originated locally and potentially read, modify, upload, or delete exposed data. Exploitation requires a browser to visit the attacker-controlled web server and depends on the consuming UPnP service configuration; impact varies by service.

CVSS severity9.8
Critical
EPSS probability0.63%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

DNS rebinding in libupnp before 1.14.6 allows remote attackers to trigger local UPnP actions through a victim browser. The embedded HTTP server accepts any Host header, allowing a DNS-rebinding site to reach services as if requests originated locally and potentially read, modify, upload, or delete exposed data. Exploitation requires a browser to visit the attacker-controlled web server and depends on the consuming UPnP service configuration; impact varies by service.

The record

CVE
CVE-2021-29462
Published
Apr 20, 2021
Updated
Aug 3, 2024
Vendor
pupnp
Product
libupnp
Classifications
CWE-20, CWE-345, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 20, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=< 1.14.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

pupnp · libupnpversion=< 1.14.6

Published CVSS scores

7.5NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NVDCVSS: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-345Insufficient Verification of Data Authenticity
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

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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