Published Jul 11, 2023Sources checked Oct 31, 2026
6.5MEDIUMCVSS out of 10
What this means
Review the available evidence
CVE-2023-29406 and is rated Medium severity with a CVSS score of 6.5. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.
What to do next
Remediation and response
Microsoft Security Response Center guidance
Vendor revision: Sep 17, 2026
CBL-Mariner Releases
Vendor-listed releases
1.21.6-1
1.20.7-1
CISA KEVNot listedBased on the latest collected catalog
EPSS1.5%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2023-29406?
The HTTP/1 client does not fully validate the contents of the Host header. A maliciously crafted Host header can inject additional headers or entire requests.
With fix, the HTTP/1 client now refuses to send requests containing an invalid Request.Host or Request.URL.Host value.