CVE-2026-94439

HTTP/1 server connection desynchronization after 2xx CONNECT response in net/http

Published Oct 8, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
When an HTTP server handler sends a 2xx response to an HTTP/1 CONNECT request and returns without hijacking the connection, the server improperly continues to read and serve requests from the connection. Since a 2xx response to an HTTP/1 CONNECT converts the connection into a tunnel, the server should not treat the connection as continuing to contain HTTP. The impact of this misbehavior is mostly limited to potential request smuggling, where an intermediate proxy considers the data on the connection to be tunneled and the server considers it to be HTTP.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-8935-1 Go vulnerabilities
History
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}

Type Values Removed Values Added
Weaknesses CWE-151
CWE-665
Type Values Removed Values Added
Weaknesses CWE-151
CWE-665
Type Values Removed Values Added
First Time appeared Go Standard Library
Go Standard Library net/http
Vendors & Products Go Standard Library
Go Standard Library net/http
Type Values Removed Values Added
Weaknesses CWE-444
References
Metrics threat_severity

None

cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}

threat_severity

Moderate

Type Values Removed Values Added
Description When an HTTP server handler sends a 2xx response to an HTTP/1 CONNECT request and returns without hijacking the connection, the server improperly continues to read and serve requests from the connection. Since a 2xx response to an HTTP/1 CONNECT converts the connection into a tunnel, the server should not treat the connection as continuing to contain HTTP. The impact of this misbehavior is mostly limited to potential request smuggling, where an intermediate proxy considers the data on the connection to be tunneled and the server considers it to be HTTP.
Title HTTP/1 server connection desynchronization after 2xx CONNECT response in net/http
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Go
Published
Updated
Oct 9, 2026, 4:52 PM
Reserved
Sep 21, 2026, 4:43 PM
Status
Awaiting Analysis
Published
Oct 8, 2026, 11:17 PM
Modified
Oct 9, 2026, 5:16 PM
Severity
Moderate
Public date
Oct 8, 2026, 10:53 PM