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Vulnerabilities

Vulnerability · CVE-2026-94439

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

Published Oct 8, 2026 · catalog updated Oct 16, 2026 · HTTP/1 server connection desynchronization

Check if you run it

No confirmed exploitation is on record for CVE-2026-94439. EPSS is 0.32%. Act only if a listed version of HTTP/1 server connection desynchronization is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (HTTP/1 server connection desynchronization).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Unknown—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.32%
Remediation
Not established
Affected products
Go stdlib

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Go stdlib0 → 1.26.9

How to fix CVE-2026-94439

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-94439. EPSS is 0.32%. Act only if a listed version of HTTP/1 server connection desynchronization is installed.

Which versions are affected?

Compare what you have installed with 0 → 1.26.9. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.32%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 8, 2026 · Go Vulnerability Database

    Detected

    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

  2. Oct 16, 2026 · Go Vulnerability Database

    Fix available

    stdlib fixed in 1.26.9

  3. Oct 16, 2026 · Go Vulnerability Database

    Fix available

    stdlib fixed in 1.26.9

  4. Oct 16, 2026 · Go Vulnerability Database

    Updated

    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

Sources

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.