CVE-2021-41442Public exploitNetwork attack vector

Web-interface interruption via conflicting HTTP length headers

Published Feb 9, 2022 · Updated Jul 9, 2026

HTTP request smuggling in D-Link DIR-X1860 firmware 1.03 and earlier allows remote attackers to interrupt the web interface. The HNAP1 API accepts conflicting Content-Length and Transfer-Encoding headers, waits for an oversized declared body, and ties up endpoint processing. No authentication is required, but repeated parallel requests are needed; the documented effect is delayed or unavailable management, including blocked logins.

CVSS severity7.5
High
EPSS probability3.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP request smuggling in D-Link DIR-X1860 firmware 1.03 and earlier allows remote attackers to interrupt the web interface. The HNAP1 API accepts conflicting Content-Length and Transfer-Encoding headers, waits for an oversized declared body, and ties up endpoint processing. No authentication is required, but repeated parallel requests are needed; the documented effect is delayed or unavailable management, including blocked logins.

The record

CVE
CVE-2021-41442
Published
Feb 9, 2022
Updated
Jul 9, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-444, T1499.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 9, 2022CVE publishedPublication date reported by the CVE source.
  2. Jul 9, 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?

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

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P

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-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1499.002Service Exhaustion Flood

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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