HTTP/1 server connection desynchronization after 2xx CONNECT response in net/http
Severity and exploitation
KEV coverage does not rule out exploitation.
Severity
unknownCVSS measures technical severity, not the likelihood of an attack.
Known exploitation
Not listed in the checked CISA KEV catalog
Absence from CISA KEV does not rule out attacks.
Public exploit
Not established by this record
Missing evidence does not mean no public exploit exists.
Remediation
Package fixes recorded
Fix versions are recorded for 1 of 1 mapped packages. Check each release branch and any separate product guidance.
What this means
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.
Source excerpt · OSVAttack conditions
No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.
Review supporting sources →Affected versions
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Packages
Compare each installed version with the publisher’s affected ranges. Where a fix is recorded, choose the appropriate release branch and test compatibility before upgrading.
| Affected range | Recorded fix |
|---|---|
| Earlier releases before 1.26.9Semantic versions | 1.26.9 |
| From 1.27.0-0 before 1.27.2Semantic versions | 1.27.2 |
Version evidence: OSV · GO-2026-6613
View original version evidence (0 explicit versions)
What to do
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Use the recorded fix for your release branch. Review the publisher’s instructions and test compatibility before upgrading.
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Public exploit evidence
No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.
Original source description
Read the full publisher 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.
References
3 sourcesInside the record
Evidence available
Describes the evidence in this view, not whether the product is safe.
Original records
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