CVE-2021-41451Public exploitNetwork attack vector

Cache poisoning via HTTP/0.9 downgrade

Published Dec 17, 2021 · Updated Jul 9, 2026

HTTP response confusion in the TP-Link Archer AX10 V1 web interface before V1_211117 allows remote attackers to expose intermediary caches to poisoning. The parser accepts GET or POST requests labeled HTTP/0.9 and answers with that obsolete version while retaining HTTP headers except Content-Length. No authentication is required; poisoning requires an intermediary cache that treats the protocol-confused response as cacheable content.

CVSS severity7.5
High
EPSS probability2.40%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP response confusion in the TP-Link Archer AX10 V1 web interface before V1_211117 allows remote attackers to expose intermediary caches to poisoning. The parser accepts GET or POST requests labeled HTTP/0.9 and answers with that obsolete version while retaining HTTP headers except Content-Length. No authentication is required; poisoning requires an intermediary cache that treats the protocol-confused response as cacheable content.

The record

CVE
CVE-2021-41451
Published
Dec 17, 2021
Updated
Jul 9, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-444
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 17, 2021CVE 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

5.0NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

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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