Description
Historically, we have been rather lax about malformed framing-related headers in our HTTP/2 implementation, as they cannot interfere with HTTP/2 framing. However, this makes it possible for our HTTP/2 implementation to forward responses containing such headers to an HTTP/1 client when acting as a reverse proxy. If the HTTP/1 client also does not behave strictly enough, this can result in response smuggling.
Published: 2026-10-08
Score: 7.5 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Fri, 09 Oct 2026 19:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-20

Fri, 09 Oct 2026 17:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-444
Metrics cvssV3_1

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

ssvc

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


Fri, 09 Oct 2026 09:15:00 +0000

Type Values Removed Values Added
First Time appeared Go Standard Library
Go Standard Library net/http
Go Standard Library net/http2
Vendors & Products Go Standard Library
Go Standard Library net/http
Go Standard Library net/http2

Fri, 09 Oct 2026 02:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-20

Thu, 08 Oct 2026 23:00:00 +0000

Type Values Removed Values Added
Description Historically, we have been rather lax about malformed framing-related headers in our HTTP/2 implementation, as they cannot interfere with HTTP/2 framing. However, this makes it possible for our HTTP/2 implementation to forward responses containing such headers to an HTTP/1 client when acting as a reverse proxy. If the HTTP/1 client also does not behave strictly enough, this can result in response smuggling.
Title HTTP/2 transport accepts malformed framing-related headers in net/http
References

Subscriptions

Go Standard Library Net/http Net/http2
cve-icon MITRE

Status: PUBLISHED

Assigner: Go

Published:

Updated: 2026-10-09T16:23:56.092Z

Reserved: 2026-08-24T23:36:15.738Z

Link: CVE-2026-78660

cve-icon Vulnrichment

Updated: 2026-10-09T16:19:44.882Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-08T23:17:03.510

Modified: 2026-10-09T17:16:49.243

Link: CVE-2026-78660

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-09T20:30:11Z

Weaknesses
  • CWE-444

    Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')