CVE-2021-33516Network attack vector

Data access via unchecked Host header

Published May 24, 2021 · Updated Aug 3, 2024

DNS rebinding in GNOME GUPnP before 1.0.7 and 1.1.0 through 1.2.4 allows remote attackers to access local UPnP services. The HTTP service accepted requests without validating that the Host header named one of its bound local addresses, so a rebinding domain could route browser requests to the service. Exploitation requires a user to visit attacker-controlled web content; resulting reads or writes depend on the UPnP actions exposed by the consuming service.

CVSS severity8.1
High
EPSS probability1.08%
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 GNOME GUPnP before 1.0.7 and 1.1.0 through 1.2.4 allows remote attackers to access local UPnP services. The HTTP service accepted requests without validating that the Host header named one of its bound local addresses, so a rebinding domain could route browser requests to the service. Exploitation requires a user to visit attacker-controlled web content; resulting reads or writes depend on the UPnP actions exposed by the consuming service.

The record

CVE
CVE-2021-33516
Published
May 24, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-200
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 24, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.1Oracle LinuxCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
8.1Canonical UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
9.4SUSECVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-200Exposure of Sensitive Information to an Unauthorized Actor

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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