Request smuggling via post-CONNECT HTTP parsing
Published Oct 8, 2026 · Updated Oct 8, 2026
Request smuggling in Go standard library net/http allows remote attackers to inject requests via HTTP/1 CONNECT. After a handler sends a 2xx response and returns without hijacking the connection, the HTTP/1 server incorrectly parses subsequent tunnel bytes as additional HTTP requests. Exploitation depends on that handler behavior and an intermediate proxy interpreting the connection as a tunnel; the documented consequence is request smuggling, not arbitrary code execution.
Summary
What happened
Request smuggling in Go standard library net/http allows remote attackers to inject requests via HTTP/1 CONNECT. After a handler sends a 2xx response and returns without hijacking the connection, the HTTP/1 server incorrectly parses subsequent tunnel bytes as additional HTTP requests. Exploitation depends on that handler behavior and an intermediate proxy interpreting the connection as a tunnel; the documented consequence is request smuggling, not arbitrary code execution.
The record
- CVE
- CVE-2026-94439
- Published
- Oct 8, 2026
- Updated
- Oct 8, 2026
- Vendor
- Go standard library
- Product
- net/http
- Classifications
- Unavailable
- Attack vector
- network
- Privileges
- Unavailable
Timeline
How it unfolded
- Oct 8, 2026CVE publishedPublication date reported by the CVE source.
- Oct 8, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <1.26.9
- Affected versionversion=1.27.0-0 <1.27.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
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.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
No sourced classifications are available.
Public exploit references
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Technologies
Your stack
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Your stack
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