Vulnerability Intelligence Report
HTTP/2 transport accepts malformed framing-related headers in net/http
CVE-2026-78660
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.
No Active Exploit Signals
CVSS Base Score
7.5
HIGH
Exploitability:3.9
Impact Score:3.6
EPSS Probability:0.19%
Executive Threat Verdict
Evaluating...
Evaluating Threat Landscape...
Assessing known weaponization, exploitation telemetry, and federal advisories.
Attack Surface
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Authentication
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Weaponization
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SSVC Action
—
Weaknesses (CWE)
CWE-444 ↗CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Affected Products & Versions
| Vendor | Product | Affected Versions |
|---|---|---|
| Go standard library | net/http | 0 < 1.26.9 (affected) |
| Go standard library | net/http/internal/http2 | 1.27.0-0 < 1.27.2 (affected) |
| golang.org/x/net | golang.org/x/net/http2 | 0 < 0.60.0 (affected) |
Threat Intelligence Signals
EPSS Score
0.188%
Identity & Timeline
| Status | PUBLISHED |
| Assigning Authority | Go Project · Vendor · USA |
| Reserved | 2026-08-24T23:36:15 |
| Published | 2026-10-08T22:53:59 |
| Last Updated | 2026-10-09T16:23:56 |
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