CVE-2026-78663 - Vulnerability Details - OpenCVE

The HTTP/2 server can refund connection-level flow control twice for the same data: Once when a client resets a stream (refunding data for any sent-but-unread portion of the stream), and again when a request handler reads the buffered data. A malicious client can exploit this to bypass the configured connection-level flow control limit (MaxReceiveBufferPerConnection). Total buffered data is still limited by the concurrent stream limit and stream-level flow control.

No CVSS v4.0

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

No data.

No data.

No data.

No data.

Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References

Link	Providers
https://go.dev/cl/847187
https://go.dev/cl/847310
https://go.dev/issue/81743
https://groups.google.com/g/golang-announce/c/U2fTuyDJznI
https://groups.google.com/g/golang-announce/c/ZPwCyRUuGBs
https://pkg.go.dev/vuln/GO-2026-6612

History

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

Type	Values Removed	Values Added
Description		The HTTP/2 server can refund connection-level flow control twice for the same data: Once when a client resets a stream (refunding data for any sent-but-unread portion of the stream), and again when a request handler reads the buffered data. A malicious client can exploit this to bypass the configured connection-level flow control limit (MaxReceiveBufferPerConnection). Total buffered data is still limited by the concurrent stream limit and stream-level flow control.
Title		Double flow control refund on HTTP/2 server streams in net/http
References		https://go.dev/cl/847187 https://go.dev/cl/847310 https://go.dev/issue/81743 https://groups.google.com/g/golang-announce/c/U2fTuyDJznI https://groups.google.com/g/golang-announce/c/ZPwCyRUuGBs https://pkg.go.dev/vuln/GO-2026-6612

Projects

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MITRE

Status: PUBLISHED

Assigner: Go

Published: 2026-10-08T22:53:59.772Z

Updated: 2026-10-08T22:53:59.772Z

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

Link: CVE-2026-78663

Vulnrichment

No data.

NVD

Status : Received

Published: 2026-10-08T23:17:03.647

Modified: 2026-10-08T23:17:03.647

Link: CVE-2026-78663

Redhat

No data.

OpenCVE Enrichment

No data.

Weaknesses

No weakness.

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"globalOptionsHandler.ServeHTTP"}, {"name": "gzipReader.Close"}, {"name": "gzipReader.Read"}, {"name": "http1ClientConn.Close"}, {"name": "http1ClientConn.RoundTrip"}, {"name": "http2ClientConn.Close"}, {"name": "http2ClientConn.Ping"}, {"name": "http2ClientConn.RoundTrip"}, {"name": "http2ClientConn.Shutdown"}, {"name": "http2ConnectionError.Error"}, {"name": "http2ErrCode.String"}, {"name": "http2FrameHeader.String"}, {"name": "http2FrameType.String"}, {"name": "http2FrameWriteRequest.String"}, {"name": "http2Framer.ReadFrame"}, {"name": "http2Framer.ReadFrameForHeader"}, {"name": "http2Framer.ReadFrameHeader"}, {"name": "http2Framer.WriteContinuation"}, {"name": "http2Framer.WriteData"}, {"name": "http2Framer.WriteDataPadded"}, {"name": "http2Framer.WriteGoAway"}, {"name": "http2Framer.WriteHeaders"}, {"name": "http2Framer.WritePing"}, {"name": "http2Framer.WritePriority"}, {"name": "http2Framer.WritePushPromise"}, {"name": "http2Framer.WriteRSTStream"}, {"name": 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"https://go.dev/issue/81743"}, {"url": "https://groups.google.com/g/golang-announce/c/U2fTuyDJznI"}, {"url": "https://groups.google.com/g/golang-announce/c/ZPwCyRUuGBs"}, {"url": "https://pkg.go.dev/vuln/GO-2026-6612"}], "credits": [{"lang": "en", "value": "Ali Sherif (https://www.linkedin.com/in/ali-sherif-13812b276/)"}]}}}