GO-2026-6612

    Dashboard / Vulnerabilities / GO-2026-6612

    GO-2026-6612

    Published: 8 Oct 2026Last Modified: 8 Oct 2026

    Summary: Double flow control refund on HTTP/2 server streams in net/http

    Details: 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.

    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

    Affected packages

    Package

    Name: stdlib

    Purl: pkg:golang/stdlib

    Affected ranges

    Type: SEMVER

    Events:

    Introduced- 0
    Fixed -1.26.9

    Affected versions

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High